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INORGANIC CHEMISTRY. 1. INTRODUCTION.
THE particular form of the Periodic Table used in inorganic chemistry is still to some extent a matter of personal preference. Advances in inorganic chemistry during 1956 are presented in this report on the basis of its " long form "; the chemistry of the main groups is discussed first and this is followed by a systematic treatment of the transition elements.
The list of atomic weights approved by the International Union of Pure and Applied Chemistry includes revised values for 12 elements : Dy, Er, Gd, Hf, In, Ni, Pd, Pt, Re, Sm, W, and Xe. The greatest change is for gadolinium which is altered from 156.9 to 157.26, and substantial modi- fications are also recommended for palladium (from 106.7 to 106.4) and platinum (from 195.23 to 195.09). The changes reflect a general tendency to favour values obtained by precise physical methods and it is significant that most of the elements mentioned above have presented unusual diffi- culties of determination by chemical means either because of difficulties in separation and purification, or because of difficulties in preparing compounds of exactly known composition.
Two new journals, both Russian, of interest to inorganic chemists began publication during 1956, Zhzurnal Neorganicheskoi Khimii and KrystaZZo- gra$yn, Reviews have appeared on the periodicity of thermodynamic properties of compounds,2 the variations and relationships of some ionization potential^,^ the lattice energy of ionic crystal^,^ the Raman spectra of inorganic compounds, the purification of the rare gases, and the chemistry of non-aqueous ~olu t ions .~ The last topic is mentioned frequently in the following sections whenever i t is relevant to. the chemistry of particular compounds, but i t is convenient here to draw attention to two further more general investigations. The first is the development of diethyl ether as a solvent for ionic reactions.8 The solvent is considered to dissociate to a minute extent as ethyl ethoxide, Et'OEt-, so that compounds like lithium ethoxide behave as bases, and complexes which the solvent forms with electron acceptors (A), and which may be formulated as E t i [EtO+A]-, behave as acids. The interpretations are based on conductimetric titrations rather than the isolation and analysis of compounds. The second investig- ation concerns a study of carbonyl chloride as an acid-base solvent ; on the basis of chlorine-exchange experiments i t is concluded that this solvent does not undergo self-ionization as C 0 2 &(Cl-), or COCl IC1- but is essentially covalent .9
E. Wichers, J . Amer. Chena. Soc., 1956, 78, 3235. B. Lakatos, Acta Chim. Acad. Sci. Hwng., 1955, 8, 207. L. H. Ahrens, J . Inorg. Nuclear Chem., 1956, 2, 290. A. F. Kapustinskii, Quart. Rev., 1956, 10, 283. L. A. Woodward, zbid., p. 185. D. S. Gibbs, H. J . Svec, and R. E. Harrington, I n d . Eng. Chem., 1956, 48, 289. V. Gutmann, Svensk kem. Tidskr., 1956, 68, 1; Quart. Rev. , 1956, 10, 451. G. Jander and K. Kraffczyk, 2. anorg. Chem., 1956, 282, 121 ; 283, 217. J . L. Hus ton , .I. Inorg. Nwclrnr Chem., 1956, 2, 128.
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84 INORGANIC CHEMISTRY.
An increasing amount is being published on the nature of non-stoicheio- metric compounds and, whilst much of the interest is in the more physical aspects of the subject, substantial advances are also being made in the chemistry of these systems. The crystal chemistry of non-stoicheiometric compounds has been reviewed.1° A careful X-ray investigation of the products of thermal decomposition of lead dioxide shows that two inter- mediate non-stoicheiometric phases with narrow composition ranges exist between PbO, and Pb304. The or-phase Pb01.50-1.62 is close to Pb7011 and the p-phase, Pbl.42-1.50, is close to Pb203.11 Refined phase diagrams in the lead-sulphur system suggest that PbS has 6 x lo1, atoms of excess of Pb per C.C. at the composition of maximum m. p., 1127".12 A series of seven discrete phases has been found in the titanium-oxygen system between TiO,.,, and TiOl.go. The compositions of these appear to be constant within &0.002 and can be represented by the formula Tin02n-l where 4 < n < 10.13 A re-investigation of the phases present in the iron-oxygen system at compositions near FeO has shown that, above lOOO", the composi- tion range of ferrous oxide is from Fe,.,,,O to Fe,.,,,O; below this temper- ature the composition limits converge and at 570" the compound has the composition Fe, 9 3 0 ; at still lower temperatures a two-phase system (or-Fe + Fe304) separates.14 The cobalt-selenium system has three inter- mediate solid phases : B-CogSe,, which is related to Cogs8 and (Fe,Ni),S,; a y-phase of NiAs structure with some vacant cation sites, which exists over the composition range CoSe,.,,,.,, at 600" ; and a &phase CoSe,, of pyrites structure.15 In the cobalt-tellurium system the p-phase has a much wider composition range (CoTe,.,-,., at 600", CoTe,.,-,., at 335") .16 The ternary compound Li,Mn,-,O formed by sintering Li,O, and MnO at high temper- atures comprises a single non-stoicheiometric phase of NaCl structure over a large range of compositions. At higher lithium concentrations, depending on the temperature, the compound LiMnO, is also f0rrned.l' Strontium- niobium bronzes with the perovskite structure and similar to the sodium- tungsten bronzes have been prepared in the composition range Sr,.,NbO,- Sro.,,Nb03. The colour changes from deep blue to red with increasing strontium content and compressed-powder specimens have a high electrical conductivity. Other phases, with complex X-ray patterns, exist between Sr,.,NbO, (white) and Sr,.68Nb0, (black) and there is also evidence for bronzes in the systems Ba,NbO, and Ba,TaO,.ls
2. MAIN GROUPS.
Group 1.-The dissolution of sodium in methylamine to give a blue solution has been shown to depend on traces of ammonia in the methyl-
lo A. D. Wadsley, Rev. Pure Appl . Chem. (Australia), 1955, 5, 165. l1 G. Butler and J. L. Copp, J. , 1956, 725. 12 J. Bloem and F. A. Kroger, 2. phys. Chem. (Frankfurt), 1956, 7 , 1. l3 S. Andersson and A. Magneli, Naturwiss., 1956, 43, 495. l4 J. Aubry and F. Marion, Compt. rend., 1956, 242, 776. l5 F. Bahm, F. Grranvold, H. Haraldsen, and H. Prydz, Acta Chem. Scund., 1955, 9,
16 H. Haraldsen, F. Grernvold, and T. Hurlen, 2. anorg. Chem., 1956, 283, 143. 1 7 W. D. Johnston and R. R. Heikes, J . Amer. Chem. SOC., 1956, 78, 3255. 18 D. Ridgley and R. Ward, ibid., 1956, 77, 6132.
1510.
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ADDISON AND GREENWOOD: MAIN GROUPS. 85
amine.19 Liquid sodium does not react with zinc phosphate below 160" and this is also the critical wetting temperature of zinc by liquid sodium if the zinc has been electropolished in a phosphate bath; no such critical temper- ature was found for abraided zinc plates2*
Extensive studies of the systems Na20-A120,-Si02 and K,O-A1,0,-SiO, have been reported.21 A new series of crystalline acid metaphosphates has been obtained from a phase study of the system N+O-H,0-P,0,.22
Rubidium and casium react with sulphur in liquid ammonia to give crystalline polysulphides of formula M2S, where x is 2, 3, or 5; these com- pounds and also cs'& were isolated and their physical properties determined. Rb2S4, Rb2S6, and Cs2S4 were not formed under these condition^.^^
It has been confirmed that czsium monoxide Cs20 has the anti-CdCI,-type of crystal structure and it remains the only known example of this structure ; the abnormally large Cs-Cs distance and the short Cs-0 distance indicate considerable polarization of the czsium ion.24 The crystal structure of tricasium monoxide has also been determined.25 The Cs-0 bond is ionic as in Cs20 but the Cs-Cs bond length is similar to that in metallic casium. Its semimetallic structure is also reflected by its low m. p. (165") and very high electrical conductivity which is one-third of that of caesium itself.
Group II.-Unipositive beryllium is obtained by anodic oxidation during the electrolysis of aqueous solutions between beryllium electrodes in a divided cell. In short runs, the Be+ ion is quantitatively oxidized by water to Be2+ with liberation of hydrogen ; in longer runs some metallic beryllium is formed by disproportionation, 2Be+ _+ Be2+ + Be, and is deposited uniformly throughout the anolyte. The existence of unipositive beryllium was further demonstrated by its ability to reduce permanganates to man- ganese dioxide and silver salts to metallic silver.26 Similar experiments with organic oxidants have confirmed that unipositive magnesium Mg+ is formed by anodic oxidation when a solution of sodium iodide in pyridine is electro- lysed between magnesium electrodes2'
Beryllium oxymonochloroacetate, Be40 (C1CH2*C02),, has been made and its X-ray cell dimensions found to be approximately the same as those of the oxypropionate Be40(MeCH2*C02)6.28 In the presence of anhydrous ethanol, beryllium oxyacetate splits off acetic anhydride to form higher basic acetates according to the equation :
Both the original oxyacetate and the higher basic acetates occlude appreci- able amounts -of the solvent .29
Be,O(MeCO,), = Be,O,'+ $- 4MeC0,- + (MeCO),O
le G. Hohlstein and U. Wannagat, 2. anorg. Chem., 1956, 284, 191. 2e C. C. Addison, W. E. Addison, D. H. Kerridge, and J. Lewis, J., 1956, 1454. 21 J. F. Schairer and N. L. Bowen, Amer. J . Sci., 1955, 253, 681; 1956, 254, 129. 22 E. J. Griffith, J . Amer. Chem. SOC., 1956, 78, 3867. 23 F. FehCr and K. Naused, 2. anorg. Chem., 1956, 283, 79.
Khi-Ruey Tsai, P. M. Harris, and E. N. Lassettre, J . Phys. Chern., 1956, 60, 338. Idem, ibid., p. 345.
26 B. D. Laughlin, J. Kleinberg, and A. W. Davidson, J . Ames.. Chem. Soc., 1956,
2 7 W. E. McEwen, J. Kleinberg, D. L. Burdick, W. D. Hoffman, and J. Y . Yang,
28 A. V. Novoselova and K. N. Semenenko, Zhur. neorg. Khinz., 1956, 1, 887. 2B H. D. Hardt, 2. anorg. Chem., 1956, 286, 254.
78, 559.
ibid., p. 4587.
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86 INORGANIC CHEMISTRY.
Magnesium hydride has very different properties depending 011 whether it is prepared directly from the elements or by pyrolysis of organomagiiesium compounds. It has now been shown by X-ray methods that both forms have the rutile crystal structure and that the differences in properties are related to the degree of subdivision of the sample.30 Calcium hydride chloride (CaHC1, m. p. 700") and its strontium and barium analogues (m. p.s 840" and 850") may be prepared either by melting together the appropriate hydride and anhydrous chloride or by heating the metal and its chloride in an atmosphere of hydrogen. The compounds, which are stable at high temperatures even under vacuum, resemble mica in appearance and have the PbClF-type crystal structure.31
The formation of calcium superoxide Ca(O,), during the dehydration of calcium peroxide octahydrate with phosphoric oxide has been discussed.32 The possibility of preparing barium superoxide Ba(O,), has also been con- sidered and the equilibrium pressure of oxygen above the compound has been calculated to be 32 atm. at 25", 75 atm. a t loo", and 2300 atm. a t 200" 33
Group II1.-The boron hydrides and their derivatives continue to attract a great deal of interest. A new B, hydride has been detected by X-ray techniques and a partial elucidation of its structure shows that the boron atoms form an icosahedral fragment similar to that formed by a juxta- position of B4H,, and B,Hl, suitably bridged to give an overall formula B,H1,.34
The effect of nitrogen-bond strain on the chemistry of aminoboron hydrides has been studied by synthesising a series of derivatives in which the nitrogen is in small heterocyclic rings.35 Dimethylaminomethylborine Me,NBH*Me, made by treating methylborine with dimethylamine, is pre- dominantly monomeric in the vapour phase but dimeric as a Diborane diammine B,H6,2NH3 reacts with alkali metals in liquid ammonia to give a borohydride and aminoborine :
M + B1H,,2NH, + &HZ + NH, + MBH4 -I- BHZ-NH,
During removal of the solvent, the aminoborine undergoes ammonolysis to an extent which depends on the metal used, increasing from potassium to lithium.37 The sodium-diborane reaction has been clarified by recognition of Na,B,H, as an intermediate; the product, which has the empirical formula NaB,H,, is actually an equimolar mixture of sodium borohydride and a new borohydride NaB3H, : 38
2Na + 2B2H6 NaBH, + NaB,H,
30 W. Freundlich and B. Claudel, Bull. SOC. chim. France, 1956, 967 ; see also Ann.
31 P. Ehrlich, B. Alt, and L. Gentsch, 2. anorg. Chem., 1956, 283, 58. 32 C. Brosset and N.-G. Vannerberg, Nature, 1956, 177, 2 3 8 ; S. 2. Makarov and
33 I. I. Volnov and A. N. Shatunina, Doklady Akad. Nauk S.S S.R., 1956, 110, 87. 34 R. E. Dickerson, 1'. J. Wheatley, P. A. Howell, and W. K. Lipscomb, J . Chew.
36 A. B. Burg and C. D. Good, J . Inorg. Nuclear Chem., 1956, 2, 237. 36 A. B. Burg and J. L. Boone, J . Amer. Chew SOC., 1956, 78, 1521. 37 G. W. Schaeffer, M. D. Adams, and F. J. Koenig, ibid., p. 725. 3 8 W. V. Hough, L. J . Edwards, and A. D. McElroy, ibid., p. 689.
Reports, 1955, 52, 99.
N. K. Grigor'eva, Zhur. neorg. Khim., 1956, 1, 1607.
Phys., 1956, 25, 606.
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ADDISON AND GREENWOOD : MAIN GROUPS. 87
The long-sought monomeric addition compound ammonia-borine H,N,BH, has now been made by the action of lithium borohydride on am- monium salts and its structure is confirmed by X-ray structural analysis.39 The preparation, characterization, and chemical reactions of the monomeric addition compounds of borine with pyridine and quinoline are described.m Diborane reacts with phosphorus trifluoride under pressure at room temper- ature to give the addition compound F,P,BH,. The properties of this somewhat unexpected compound are very similar to those of the carbonyl derivative OC,BH, and its ethane-like structure has been confirmed by Raman spectro~copy.~~ The relative ability of borine, boron trifluoride, and trimethylboron to co-ordinate with the dialkyls of oxygen, sulphur, and selenium has been compared.42
A kinetic study of the reaction of decaborane B1,H,, with low-molecular weight alcohols to give borate esters and hydrogen is reported.43 Unlike the lower boranes, decaborane dissolves in aqueous solutions of alcohols or dioxan without rapid hydrolysis and the rate of hydrogen .evolution exhibits a marked induction period. I t is now found that decaborane forms a monobasic acid in these solutions without the evolution of hydrogen, that the decaborane is partly recoverable, and that the solutions can be potentio- metrically titrated with aqueous sodium hydr~xide.~,
Borohydrides can be prepared by a new method involving the hydrolysis of magnesium boride MgB, with bases such as potassium hydroxide or tetra- methylammonium hydroxide.45 Trisubstituted borohydrides of the type Na[B(OR),*H], which are readily prepared by the addition of sodium hydride to alkyl borate esters, are more powerful reducing agents than sodium boro- hydride itself. This is attributed to the greater ease of removing a hydride ion from [B(OR),*H]-, because B(OR), is a weaker acceptor than borine, BH,.46 Tetra-alkoxyborohydrides are prepared similarly, the sodium hydride being replaced by sodium alk~xide.~' The addition compounds of lithium borohydride and lithium aluminium hydride with tetrahydrofuran and tri- methylamine, and of aluminium hydride itself with tetrahydrofuran, have been investigated.
An elegant series of experiments on the nuclear magnetic resonance spectrum of aluminium borohydride shows that Al(BH,), dissociates re- versibly at 80" into diborane and a new compound A12B4H1, : 49
ZAIB,H,, e. B,H, + AI,B,H,,
39 S. G. Shore and R. W. Parry, J . Amer. Chem. SOL., 1955, 77, 502; E. L. 6084; E. W. Hughes, ibid., 1956, 78, Lippert and W. N. Lipscomb, ibid., p. 503.
40 V. I. Mikheyeva and Ye. M. Fedneva, Zhur. neorg. Khim. , 1956, 1, 894. 4 1 R. W. Parry and T. C . Bissot, J . Amer. Chem. SOC., 1956, 78, 1524; R. C. Taylor
and T. C. Bissot, J . Chem. Phys., 1956, 25, 780. 42 W. A. G. Graham and F. G. A. Stone, Chem. and Ind. , 1956, 319. 43 H. C. Beachel and T. R. Meeker, J . Amer. Chem. SOC., 1956, 78, 1796. 44 G. A. Guter and G. W. Schaeffer, ibid., p. 3546. 4 5 A. J. King, F. A. Kanda, V. A. Russell, and W. Katz, ibid., p. 4176. 4 6 H. C. Brown, E. J. Mead, and C. J. Shoaf, ibid., p. 3616. 4 7 H. C. Brown and E. J . Mead, ibid., p. 3614. 4 8 E. Wiberg and W. Gosele, 2. Naturforsch., 1956, l l b , 485; idem, ibid., p. 486;
E. Wiberg, H. Noth, and R. Uson, ibid., p. 487; E. Wiberg and A. Jahn, ibid., p. 489; E. Wiberg, H. Noth, and R. Uson, ibid., p. 490.
49 R. A. Ogg and J. D. Ray, Discuss. Faraday Soc., 1955, 19, 239, 246.
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88 INORGANIC CHEMISTRY.
All protons in aluminium borohydride are chemically equivalent and very similar to those in a simple borohydride ion BH,- ; moreover, all the protons are covalently bonded to both aluminium and boron and the three boron atoms are covalently bonded tetrahedrally to four equivalent protons. These findings cannot be reconciled with a static model of the molecule, or with intermolecular exchange of borohydride ions or rotation within each molecule. The only tenable explanation appears to be in terms of a quantum-mechanical tunnel effect.49 Perhaps the simplest representation of the compound is (1) in which a double line represents bridge-bonding with two protons between the aluminium atom and a boron atom. The second borohydride may be similarly represented by (2).
Boron trifluoride addition compounds have been studied by a variety of techniques. Nuclear resonance spectra indicate that the structure of boron trifluoride hydrates depends on the rate of crystallization : slowly cooled samples are un-ionized (BF,,H,O and BF3,2H20) whereas more rapidly cooled samples retain some of the ions which characterize the compounds in the molten state (e.g., H,0+BF3*OH-).m Boron trifluoride forms a 1 : 1 compound with urea which melts a t 82"; above 125" the compound decomposes to ammonium fluoroborate, boron nitride, and polymeric hydro- gen cyanate, from which it is concluded that boron is bonded to nitro- gen rather than oxygen in the complex.51 Boron trifluoride-dinitrogen tetroxide, which does not melt in a sealed tube at 300", is insoluble in non- polar solvents, and rapidly nitrates benzene, has been formulated as an ionic compound N02+(BF3.N0,)-.52 A complete structure determination of boron trifluoride-pyridine has shown that the B-N bond length (1.53 A) is shorter in this compound that in other boron complexes in which nitrogen is the ligand (167-1.64 A).% It is, however, comparable with the value of 1-56 found for H3N,BH,.39 Stable 1 : 1 complexes of boron trifluoride, hydrogen fluoride, and the methylbenzenes have been isolated. These com- pounds melt below room-temperature and have a high specific electrical con- ductivity (about 10-2 ohm-l cm.-l) ; they may be formulated as ArH+BF4- (Ar = Me*C6H5, m-Me,C,H,, s-Me3C6H3, as-Me,C,H,) .54 The corresponding compounds formed by replacing hydrogen fluoride by either ethyl fluoride or formyl fluoride have also been isolated and have similar proper tie^.^^
The molar heats of solution of the boron trihalides in nitrobenzene, and the heats of reaction of the trihalides with pyridine in nitrobenzene are reported and lead to the unexpected result that, under these conditions, the electron-acceptor strength increases in the order BF, < BCI, < BBr3.56
6o P. T. Ford and R. E. Richards, J., 1956, 3870. 61 H. J. Becher, Chem. Bey., 1956, 89, 1691. S2 G. B. Bachman, H. Feuer, B. R. Bluestein, and C. M. Vogt, J . Amer. Chem. SOC.,
63 2. V. Zvonkova, Kristallograjiya, 1956, 1, 73. b4 G. OlAh, S. Kuhn, and A. PavlAth, Nature, 1956, 178, 693. 65 G. OlAh and S. Kuhn, ibid., p. 1344. 66 H. C. Brown and R. R. Holmes, J . Amer. Chem. Soc., 1956, 78, 2173.
1955, 77, 6188.
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ADDISON AND GREENWOOD MAIN GROUPS. 89
Boron trifluoride is not ammonolysed by liquid ammonia in the temper- ature range -78" to +50° unless an alkali metal is also present in the solution. 57 Furthermore, the addition compound boron trifluoride-ammonia, which can be isolated from solutions of boron trifluoride in liquid ammonia, reacts with solutions of the alkali metals in ammonia in a way which varies markedly with the particular metal chosen : with potassium and ca ium the reacting mole-ratio of metal to complex is 1 : 1, with sodium the ratio is 2.5 : 1 and with lithium 3 : 1, though in the last case temporary end-points could be detected at the two smaller ratios as well. The following reaction schemes have been suggested to represent the overall stoicheiometry and the products formed : 58
BF,,NH, + K = NHZ*BFz + KF + +Ha 2BF,,NH3 + 5Na + 2NHB = (NH,),B(NH).BF(NH,) + 5NaF + 24H, 2BF,,NH3 + 6Na + 2NH3 = (NH,),B(NH)*B(NH) + 6NaF + 3H,
Ammonolysis of boron tri-iodide on the other hand proceeds rapidly in liquid ammonia even in the absence of alkali metals. The products are ammonium iodide and boron imide B2(NH),.59 Studies of the effect of steric strain on the reaction rate and heat of reaction of substituted pyridine bases with diborane, boron trifluoride, and trimethylborine continue.60
Phase studies have confirmed the existence of the addition compound boron trichloride-acetyl chloride in the solid state despite the fact that above the m. p., -54", the vapour pressure of the system shows a positive deviation from ideality. There is no compound in the system boron trichloride- benzoyl chloride, and neither system shows catalytic activity, in contrast to the behaviour of these ligands with gallium trichloride.61 The crystal structure of the addition compound between diboron tetrachloride and ethylene shows that the structure of the molecule is a zig-zag chain C12B*CH2*CH,-BCl,, in agreement with chemical evidence. 62
A new class of organoboron compound, RBXoOR', in which two of the halogens in BX, have been replaced by an alkyl (or aryl) and an alkoxy- group has been reported.63 The thermal stability, solvolysis, and co-ordin- ation reactions of these compounds and the related series RB(OR), and RBX, were studied as well as the preparation and stability of dialkyl chloro- boronates C1B(OR),.64 A series of triaryl borates were prepared by the reaction of boron trichloride with substituted phenols or naphthols and their amine addition compounds investigated for steric and polar influences. 65
The studies have also been extended to include the interaction of unsaturated alcohols and ethers with boron trichloride.66 Some convenient procedures
5 7 W. A. Jenkins, J . Amer. Chem. SOC., 1956, 78, 5500. 68 W. J. McDowell and C . W. Keenan, ibid., p. 2065. 59 Idenz, zbid., p. 2069. 6o H. C. Brown, D. Gintis, and H. Podall, ibid., p. 5375; H . C. Brown and D. Gintis,
ibid., p. 5378; H . C. Brown and L. Domash, ibid., p. 5384; H . C. Brown, D. Gintis, and L. Domash, ibid., p . 6387.
N. N. Greenwood and K. Wade, J., 1966, 1627.
Idem, ibid., p. 1540; M . F. Lappert, ibid., p . 1768.
6a E. B. Moore and W. N. Lipscomb, Acta Cryst., 1956, 9, 668. 63 P. B. Brindley, W. Gerrard, and M. F. Lappert, J., 1956, 824.
66 T. Colclough, W. Gerrard, and M. F. Lappert, ibid., p. 3006. 66 W. Gerrard, M. F. Lappert, and H. B. Silver, ibid., p . 3286.
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'30 INORGANIC CHEMISTRY.
for the preparation of primary, secondary, and tertiary alkyl borate esters have been outlined.67
Unipositive aluminium is formed by anodic oxidation when aqueous solu- tions are electrolysed between an aluminium anode and a platinum cathode.68 This is similar to the behaviour of beryllium and magnesium anodes men- tioned on p. 85.
The Raman spectra of several methylaluminium halides of the type Me,AlX and MeAlX, (X = C1, Br, or I) indicate that the compounds are dimeric, the bridging occurring via two methyl groups in each case rather than via halogen atoms as had formerly been supposed. Trimethylindium is m0nomeric.6~
The crystal structure of the addition compound AlBr,,H,S, and the fact that solutions of the complex in organic solvents are acidic and can be electrolysed to give hydrogen at the cathode, support the formulation Hi (AlBr,*SH)-. 7O The determination of the solubility of aluminium chloride by a new experimental method reveals weak complex formation with aromatic hydrocarbons at room temperature which disappears a t about 70°.71 The interaction of aluminium bromide with olefins and benzene was further studied. 72 The kinetics of bromine-exchange between ethyl bromide and aluminium bromide in carbon disulphide has been interpreted as indicating that carbonium ions are not involved in the reaction.73
The constitution of gallium dichloride has been resolved ; Raman spectra show it to be Ga+GaCl,- in the molten state 74 and X-ray data confirm this structure for the solid also.75 Further reduction of the dichloride by metallic gallium can be achieved in the presence of aluminium trichloride :
GaGaCI, + 2Ga + ZAICI, = 4GaAIC1,
All the gallium is then present in the unipositive state and the product, GaAlCl,, m. p. 176", is very similar to the dichloride itself, GaGaCl,, m. p. 17Oo.''j (Bismuth trichloride may likewise be quantitatively reduced with metallic bismuth in thepresence of aluminium trichloride to give the uni- valent bismuth salt BiAlCl,, m. p. 253", and cadmium chloride gives 72% conversion into the corresponding CdAlCl,. 76)
Addition compounds of gallium trichloride with alkyl halides have been investigated tensimetrically and by phase diagrams, 7 7 and a similar in- vestigation is reported for the addition compounds of gallium trichloride with acyl chlorides.61
Trimethylindium is a stronger electron-acceptor than trimethylthallium
6 7 H. C. Brown, E. J . Mead, and C . J. Shoaf, J . Anzer.. Chem. SOC., 1856, 78, 3613. 6 8 E. Raijola and A. W. Davidson, ibid., p. 556. 69 G. P. van der Kelen and M. A. Herman, Bull. SOC. chim. belges, 1956, 65, 362. 70 A. Weiss, R. Plass, and A. Weiss, 2. anorg. Chem., 1956, 283, 390. 71 F. Fairbrother, N. Scott, and H. Prophet, J., 1956, 1164. 72 F. Fairbrother and K. Field, ibid., p. 2614. 73 F. L. J. Sixma, H. Hendriks, and D. HoltzapffeI, Rec. Trav. chim., 1956, 75, 127;
74 L. A. Woodward, G. Garton, and H. L. Roberts, J . , 1956, 3723; L. A . Woodwart1
75 G. Garton and H. &I. l'owell, personal coniniunication ; see also ref. 76. 7 6 J. D. Corbett and K. K. McMullan, J . Amer. Chem. SOC., 1956, 78, 2906. 7 7 R. Wong and H. C. Brown, J . Inorg. Nuclear Chenz., 1955, 1, 402.
F. L. J. Sixma and H. Hendriks, Proc. k . ned. Akad. Wetemchap., 1956, 59, B, 61.
and -4. A. Kord, ibid., p. 3721.
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ADDISON AND GREENWOOD : MAIN GROUPS. 91
so that the order of acceptor character of the Group 111 trimethyls towards a ligand like trimethylamine is B < A1 > Ga > In > T1. The thermal and chemical stability of derivatives such as (Me,Tl*SMe),, obtained from the reaction of Me2T1F with NaSMe in methanol, indicate that thallium and possibly indium may form dative x bonds to sulphur and selenium.78 The dipole moments of some addition compounds of indium and thallium tri- halides with ethers and cyclic nitrogen-containing ligands have been pub- lished. 79
Group 1V.-Considerable progress has been made in the field of graphite compounds and other molecular compounds of the layer-lattice type which may be prepared by intercalation. Over 30 new graphite compounds have been prepared : intercalation is most probable with chlorides of multivalent transition elements in their higher oxidation states but also occurs with the chlorides of certain lanthanide metals and of iodine. In addition, the chlorides of all Group I11 elements form graphite compounds but these can be hydrolysed, in contrast to the compounds formed by the transition elements.80 The results suggest that intercalation involves transfer of electrons from the conduction band of graphite to the cation of the reacting halide and cannot be interpreted in terms of sieve action or dipole inter- action.81 It appears that any substance may intercalate any other substance provided that electron donor-acceptor interaction is possible and that the host can provide physical accommodation by lattice expansion-a layer lattice is not essential. On the basis of these ideas i t was predicted that boron nitride, aluminium diboride, and chromium trichloride should be able to act as host and should be able to occlude oxides, sulphides, and oxyhalides as well as chlorides. This was found to be the case.82
There is no radiochemical exchange between graphite ferric chloride C,,FeCl, and ferric ions. 83 High-resolution electron diffraction and X-ray powder photography show that single layers of ferric chloride lie between successive parallel layers of graphite. The infrared spectrum of graphite oxide has been further i n ~ e s t i g a t e d . ~ ~ It is curious that, although graphite takes up 24 times its weight of iodine monochloride and about a third of this amount of bromine, neither chlorine nor iodine alone is noticeably inter- calated.*6 Solutions of the alkali metals in liquid ammonia react with graphite to give compounds of ideal formuk C12M(NHJ2, in which there are alternate layers of graphite and alkali ammine, and C,,M(NH,), in which every third layer of the graphite lattice is replaced. Lithium and methyl- amine give a similar compound C,2Li(MeNH,),.87
Carbon tetraiodide is not solvolysed by liquid ammonia near its b. p. but reversibly forms the addition compound, CI4,2NH,. However, in
i 8 G. E. Coates and R. A. Whitcombe, J. , 1956, 3351. 70 I . A. Sheka, J . Gen. CJzem. (U.S.S.R.), 1956, 26, 25. 8o R. C. Croft, Austral. J . Chem., 1956, 9, 184. 81 Idem, ibid., p . 194. 82 Idem, ibid., p p . 201, 206. 83 R. M. Lazo and J . G. Hooley, Caitad. J . CIaem., 1956, 34, 1574.
J. M. Cowley and J . A. Ibers, A d a Cryst., 1956, 9, 421. a 6 D. IIadii and A. Novak, Trans. Faraday Soc., 1955, 51, 1614. t ~ * W. Rudorff, V. Sils, and R. Zeller, 2. anorg. Chem., 1956, 283, 299.
W. Riidorff, W. Schulze, and 0. Rubisch, ibid., 1966, 282, 232.
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92 INORGANIC CHEMISTRY.
the presence of potassium amide there is a base-catalysed reaction CI, + NH,* CHI, + INH,, and the iodine amide reacts further with potassium amide to give hydrazine : INH, + KNH, + N2H4 + KI.88
An improved synthesis of thiocyanogen (CNS), has been described; the compound forms addition products with boron trifluoride and trichloride, and its derivative potassium cyanosulphite, K(NCSO,), was prepared from potassium cyanide in liquid sulphur dioxide. 89 Selenosemicarbazide, NH,-CSe*NH*NH,, has been synthesised by isomerising hydrazine seleno- cyanate in the presence of aldehydes or ketones and then hydrolysing the selenosemicarbazone so formed.g0
Polymeric silicon subhydride (SiH), is formed by the reaction of tri- bromosilane with magnesium.g1 Silicon tetrabromide and magnesium give the sub-bromide (SiBr),, but when the tetrabromide reacts with silicon at 1200°, silicon dibromide (SiBr,), is formed, together with the well known compound Si,Br,. The dibromide gives dialkyls with Grignard reagents, is reduced by lithium aluminium hydride, and hydrolyses to the subsilicic acid [Si(OH),.,],.92
In a series of experiments on the hydrolysis of trichlorosilane and its derivatives, a crystalline silicon oxyhydride (HSiO,.,), was synthesised and shown to have a " mica-like " structure which could be formulated as the two-dimensional polymer (3). This could be dehydrogenated at 507" in stages which correspond to the reactions :
H,Si,Oa __t H4Si,0a H&O, Si,O, (i .e., Si,O,)
It is suggested that the structure of the sesquioxide is similar to (3) except that Si-H bonds within each sheet are replaced by Si-Si bonds between
I 0
I S i H ,
'0, ,o' ' O\ lo SiH S i H I I
/Y "'i i"'
MelSi
\ CH2 /s iMe2
H'C I / siY 7 4 2
MeS i - -CH2- S i Me I I
S i Me2
adjacent sheets. When alkyltrichlorosilanes RSiCl, were hydrolysed the product depended on the size of the alkyl group. The ethyl derivatives gave a sheet polymer like (3) :
nEtSiCI, + I-5nH20 + (EtSiOl.&, + 3nHCI
The tert.-butyl derivative on the other hand was sterically hindered from complete polymerization and formed the tetramer (ButSiO,.,) , ; isopropyl-
88 G. W. Watt, W. R. McBride, and D. M. Sowards, J. Amer. Chem. SOC., 1956, 78,
*O R. Huls and M. Renson, Bull. SOC. chim. belges, 1956, 65, 209, 611.
@2 M. Schmeisser and M. Schwarzmann, 2. Naturforsch., 1966, l l b , 278.
1562. F. See1 and E. Miiller, Chem. Ber., 1955, 88, 1747,
G. Schott, W. Herrmann, and E. Hirschmann, Angew. Chem., 1966, 68, 213.
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ADDISON A N D G R E E N W O O D MAIN GROUPS. 93
trichlorosilane gave some tetramer (4) and some mica-like polymer (3) .93 The structure of the tetramer has been shown by X-ray analysis to be the same as that of adamantane and hexamethylenetetramine with which it is isosteric-( RSi) 406, (HC) 4(CH2)6, and N,(CH,),.94 Hexathia-adamantane (CH),S6 also has the same molecular structure, the six sulphur atoms forming a regular octahedron about the tetrahedron of carbon atoms.95
Silicon tetrachloride reacts with ammonia to give silicon di-imide and ammonium chloride as the only products and the compound formulated as SiC14,6NH, is in fact Si(NH), + 4NH,CLS6
The chemistry of silyl compounds has been rev ie~ed .~ ' Trisilylamine (SiH,),N has been shown by electron diffraction to have a planar skeleton with the nitrogen atom surrounded by three silicon atoms at the corners of an equilateral triangle. This shape, together with the abnormally short Si-N bond length, implies partial double-bonding by back-donation of the nitrogen lone-pair electrons into d orbitals of the silicon atoms, and is consistent with the chemistry of the compo~nd.~8 The recently prepared tetrasilylhydrazine (SiH,),N*N(SiH,), also has negligible donor or acceptor proper tie^.^^ Silyl isocyanide SiH,NC and isothiocyanate SiH,NCS have been prepared and their physical properties reported.100 Further work on the infrared and Raman spectra of disiloxane (SiH,),O has been interpreted on the basis of a structure in which the silyl groups rotate freely about a linear 5-0-5 axis.lo1 This is a t variance with an earlier interpretation on the basis of an asymmetric-top model.
A new series of cyclic organosilicon compounds has been obtained by rapid, low-pressure pyrolysis of tetramethylsilicon at 720". The compound Si,C,H,, has the structure (5), one methyl group of which is sometimes replaced by hydrogen to give Si,C,H,,. Another compound isolated had the formula Si,C,,H,, ; it melted at 106" and may be assigned the structure (6).lo2
The chemistry of germanium has been comprehensively reviewed.lo3 Germanium monoxide is formed by the action of carbon dioxide on german- ium at 700-900" : Ge + CO, + GeO + C0.lo4 Trichloromonogermane GeHCl,, which is best prepared by the low-temperature reaction of hydrogen chloride on germanium sulphide, is more unstable than formerly supposed and readily loses HC1 at -30" to give germanium dichloride; this in turn rapidly disproportionates to germanium and the tetrachloride via inter- mediate polymeric subchlorides. lo5
Lead fluoride reacts with alkali fluorides to form addition compounds E. Wiberg and W. Simmler, 2. anovg. Chew., 1966, 283, 401.
94 G.-M. Schwab, J. Grabmaier, and W. Simmler, 2. phys. Chem. (FrankJuyt), 1966,6,
96 E. K. Andersen and I. Lindqvist, Arkiv Kemi, 1956, 9, 169.
9 7 A. G. MacDiarmid, Quart. Rev., 1966, 10, 208. 88 K. Hedberg, J . Amer. Chem. Soc., 1955, 77, 6491. 99 B. J. Aylett, J . Inorg. Nuclear Chem., 1956, 2, 325.
loo A. G. MacDiarmid, ibid., p. 88. lol R. C. Lord, D. W. Robinson, and W. C. Schumb, J . Amer. Chem. SOC., 1966, 78,
lo2 G. Fritz and B. Raabe, 2. Nalurfovsch., 1956, l l b , 57. lo3 E. Gastinger, Fortschr. chem. Forsch., 1955, 8, 603. lo4 Idem, 2. anorg. Chem., 1956, 285, 103. lo6 C. W. Moulton and J. G. Miller, J . Amer. Chem. SOC., 1956, 78, 2702.
376.
M. Billy, Compt. rend., 1956, 242, 137.
1327.
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94 I NOKG.\N IC CHEMISTRY.
whose formulze depend on the ionic radius of the alkali metal. Potassium forms K,PbF,, whereas rubidium and czsium form the perowskite-type MPbF,. In addition, potassium and rubidium also form the non-stoicheio- metric compounds M,,Pb,_,F,-,, where n = 0.2-0.3 ; these crystallize in the anti-a-AgI structure with additional fluoride ions.lo6
Group V.-A redetermination of the electrochemical properties of liquid ammonia over a range of temperature leads to a specific conductivity of 1.97 x The thermoelectric properties of nietal-ammonia solutions cannot be interpreted on ionic or semiconductive mechanisms and imply a quantum-mechanical tunnel process for electron transport.lo8
Improved syntheses of hydrazine,log NN-disubstituted hydrazines, l10
and hydroxylamine ll1 have been described. The product of the reaction of nitric oxide with potassium sulphite (K,SO,,BNO), which was recently shown to be the potassium salt of nitrosohydroxylaminesulphonic acid ON*N(OH)*SO,H, can also be prepared by nitrosating hydroxylamine monosulphonate with an alkyl nitrite in alkaline so1ution.ll2 The constitu- tion of hydroxylamine-0-sulphonic acid H,N*O*SO,H (sometimes called sulphoperamidic acid) ha5 been further studied. The compound, which may be made by direct addition of hydroxylamine to sulphur trioxide, reacts with diazomethane to give the trimethyl derivative Me,N*O-SO, rather than the expected monomethyl derivative H,N-O*SO,Me. Since the trimethyl derivative has an X-ray pattern which is identical with that of the addition compound formed between trimethylamine oxide and sulphur trioxide Me,NO,SO,, the previously rejected formula for sulphoperamidic acid H,&*O*sO, should be re~0ns idered . l~~
Several reviews have been written on the structure and reactivity of dinitrogen tetroxide.ll* The electrical conductivity of the liquid is 1000 times less than that of the solid at -20" and is 2-36 x lo-', ohm-l cm.-l at 170.115 Molecular addition compounds of dinitrogen tetroxide with cyclic ethers 116 and with a range of nitrogen, oxygen, and aromatic hydrocarbon donors 117 have been reported. Certain of these systems, for example those with ethyl acetate and 9-tolyl cyanide, show two distinct liquidus ciu-ves and imply that the complexes may have two different m. p.s.l18
ohm-l cm.-l a t -38.9" and an ionic product of 10-29*1.107
lo6 0. Schmitz-Dumont and G. Bergerhoff, 2. anorg. Chem., 1956, 283, 314. lo' J . Cueilleron and RI. Charret, Bull. SOC. chim. France, 1956, 798, 800; Cotupf.
Io8 G. Lepoutre and J . F. Dewald, J. Amer . Chem. SOC., 1956, 78, 2953, 2956. IoS L. F. Audrieth, U. Scheibler, and H. Zimmer, ibid., p. 1852. 110 R. A. Rowe and L. F. Audrieth, ibid., p. 563. l l 1 R. E. Benson, T. L. Cairns, and G. M. Whitman, ibid., p. 4202. 112 E. Degener and F. Seel, 2. anorg. Chem., 1956, 285, 129. 113 U. Wannagat and K. Pfeiffenschneider, Naturwiss., 1956, 43, 178. 114 P. Gray and A. D. Yoffe, Quart. Rev., 1955, 9, 362; idem, Chem. Rev., 1955, 55,
1069; C. M. S. Teese and A . G. Whittaker, J. Chem. Phys., 1956, 24, 776; A. G. Whit- taker, ibid., p. 780; C. C. Addison, Kec. Trav. claim., 1956, 75, 626; 2. G. Szab6, L. G. Bartha, and B. Lakatos, J . , 1956, 1784; T. M. Oza and V. T. Oza, J . Arne$/. Chew. SOC., 1956, 78, 3564.
rewd., 1956, 242, 521.
R. S. Bradley, l'?,ans. Faraday SOC., 1956, 52, 1255. 116 H. H. Sisler and P. E. Perkins, J. Awzer. Chem. SOC., 19.56, 78, 1135. 1 1 7 C. C. Addison and J . C. Sheldon, J., 1956, 1941.
Idp???, ihid., p. 2709.
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ADDISON ANI) GREENW001) : M A I N GROUPS. 95
Dinitrogen tetroxide oxidises dialkyl sulphides smoothly to sulphoxides R2S0 without any formation of the corresponding sulphone K,S02, and also oxidises trisubstituted phosphines to phosphine oxides R,PO. Since the sulphoxides formed 1 : 1 addition compounds with dinitrogen tetroxide in contrast with the sulphones and phosphine oxides, it was concluded that sulphur was the electron donor in the s u l p h o ~ i d e s . ~ ~ ~ The reactions of di- nitrogen tetroxide with mercury,120 and with copper, zinc, and uranium in the presence of organic electron-donor solvents have also been investigated.I2l
The electrical conductance of anhydrous nitric acid and of solutions of water and dinitrogen pentoxide in nitric acid have been interpreted in terms of the self-ionic dissociation :
2HNO3 NO,' -t NOS- -t- HZO.
,4t -10" the conductivity of the pure acid is 3-67 x and this corre- sponds to a mole-fraction dissociation constant of 9.30 x in agreement with the results of cryoscopic measurements. The addition of water lowers the conductivity of the pure acid owing to a repression of the dissociation.122
A systematic study of the ultraviolet spectra of solutions of sodium nitrite in aqueous sulphuric acid shows that below 40% acid the spectrum is essentially that of nitrous acid and above 70% acid is that of the nit.rosonium ion NO ; at intermediate concentrations the nitrous acidium ion H2N0,+ is an important constituent, and equilibria involving the three species have been calculated. Similar results were obtained for aqueous phosphoric acid solutions of sodium nitrite, but in concentrated hydrochloric acid there is almost total conversion into nitrosyl ch10ride.l~~ The equilibrium between the nitrosonium ion and nitrous acid in aqueous perchloric acid has also been investigated spectrophotometrically.124
Addition compounds of nitrosyl chloride have been studied by chemical exchange of radioactive chlorine.126 Dinitrosyl pyrosulphate has been formulated as an ionic compound (NOi),S20,2- on the basis of its high m. p. 233" and low molecular weight in sulphuric acid ; i t is rapidly solvolysed by water, alcohols, ammonia, and methylamine, and reacts with a variety of other compounds.12i
The infrared, Raman, and nuclear magnetic spectra of nitryl fluoride all support the plane-triangular structure 0,NF rather than the zigzag formula ONOF.l28 The reactions which occur when nitryl fluoride dissolves in sulphuric, selenic, and phosphoric acids have been studied by following the conductivity and other physical properties of the Nitryl
The chemistry of the nitrosonium ion has been reviewed.12j
llS C. C. Addison and J. C. Sheldon, J. , 1956, 2705. 1x1 E. S. Freeman and S. Gordon, J . Ame7,. Chem. SOL. , 1956, '78, 1813. 121 C. C. Addison, J . C. Sheldon, and (in part) I?i. Hodge, J . , 1956, 3900. l Z 2 W. H. Lee and D. J . hlillen, ibid., p. 4463. lZ3 N. S. Bayliss and I>. W. Watts, ,4ustral. J . Chem., 1956, 9, 319. lZ4 K. Singer and P. A . Vamplew, J . , 1956, 3971. lZ5 F. Seel, Angew. Chem., 1956, 68, 272; see aleo <*. C . Addison and J . Lewis, Quart.
126 J. Lewis and D. B. Sowerby, Rec. l r a v . chim.. 1956, 75, 615. lZ7 U. Wannagat and G. Hohlstein, 2. anorg. Chem., 1956, 284, 177. 1 2 8 R. E. Dodd, J. A. Rolfe, and L. A. Woodward, Trans. Faraday SOC., 1956, 52,
12s G. Hetherington, D. R. Hub, and P. L. Robinson, J. , 1955, 4041.
lt'eu., 1955, 9, 115.
145; R. A. Ogg and J . R. Ray, J - Chem. Phys., 1956, 25, 79'7.
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96 INORGANIC CHEMISTRY.
chloride when dissolved in polar solvents chlorinates rather than nitrates alkylbenzenes. This is contrary to expectations and may be due to re- action with traces of moisture to give free chlorine : 3N02C1 + H,O + C1, + NOCl + 2HN0,. In agreement with this, reactive solutions were found to have the same spectrum as nitrosyl chloride whereas non-reactive solutions in non-polar solvents were colourless. 130
Fluorine analogues of the phosphoronitrile chlorides (PNCl,), cannot be synthesised by methods used for the chlorides or by fluorination of the chlorides with normal reagents ; however, the compounds (PNF,), and (PNF,) have now been successfully prepared by fluorinating the correspond- ing chlorides with solid potassium fluorosulphite KS0,F. Both compounds are volatile solids melting at 27.1" and 30.4" respectively and boiling at 51.8" and 89.7"; they are stable up to 300" but a t higher temperatures give colourless liquid polymers (PNF,),.l31
Phosphorus pentachloride PC14+Pc&- reacts with an equivalent amount of arsenic trifluoride in arsenic trichloride to give the compound PCI,+PF,-, a hygroscopic salt which sublimes with some decomposition a t 135". It should be noticed that this compound has the same empirical formula as the mixed halide PF3Cl, which is a gas at room temperature.132 PCl,+PF6- decomposes above 70" to give phosphorus pentafluoride and the new com- pound PC1,F which exists as a non-polar liquid and an ionic solid PCl4+F-.lu Considerable progress has been made in the formulation of the products of addition of bromine to phosphorus trichloride : the stable mixed halide of empirical formula PC1,.6,Bro.,, has a face-centred cubic lattice with 12 phosphorus atoms in the unit cell, P12C156Br4. Further analysis shows that the structure is 8PC14+4PC16-4Br-.134 Conductance experiments on solutions of phosphorus pentabromide in acetonitrile indicate that the compound iOniSeS in this solvent as PBr4+PBr6-. 135
Pyrophosphoryl chloride P,0,C14 and tetraphosphoryl chloride P40,C1,0 have been prepared together with phosphoryl chloride by the reaction of phosphorus trichloride with dinitrogen tetroxide, and their structure, physical properties, and chemical reactions studied.136 The complex mixture of products resulting from the mild alkaline hydrolysis of the phosphorus trihalides has been separated chromatographically and a new isohypophosphate identified. This compound, which has the formula Na,(HP,O,), has been ascribed the structure (7) and differs from the hypo- phosphate Na,H(P,O,) (8) in having no P-P bond.137
The co-ordination chemistry of phosphorus oxychloride and other multi- valent chlorides of elements in Groups V and V I was discussed at the Amsterdam Conference, and new data were presented on the electrical con-
lSo M. J. Collis, F. P. Gintz, D. R. Goddard, and E. A. Hebdon, Chem. and Irtd., 1955,
lS1 F. Seeland J. Langer, Angew. Chem., 1956, 68, 461. 13a L. Kolditz, 2. anorg. Chem., 1956, 284, 144. lSs Idem, ibid., 1956, 286, 307. 134 A. I. Popov, D. H. Geske, and N. C. Baenziger, J . Amer. Chem. SOC., 1956, 78,
lSb Idem, ibid., p. 4617. lS8 R. Klement and K. H. Wolf, 2. anoug. Chem., 1956, 282, 149. lS7 E. Thilo and D. Heinz, ibid., 1955, 281, 303.
1742.
1793; see also G. S. Harris and D. S. Payne, J., 1956, 4613.
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ADDISON AND GREENWOOD : MAIN GROUPS. 97
ductivity and heat of dissociation of the complex TiC14,2POC1,.138 The confusion which has existed about the composition of complexes formed between phosphorus oxychloride and the tetrachlorides of zirconium and hafnium has been clarified by a careful phase study of the system ZrC1,-POC13. Two compounds were found, ZrCl,,POCl,, m. p. 205", and ZrC1,,2POC13, m. p. 184-7°.139 This agrees with the results of cryoscopic work in nitro- benzene. 140 Distillation gives a product of constant composition which may be represented approximately as 321-C1,,2POCl,,~~~ but this is presumably an azeotrope rather than a definite compound. The complexes of phosphorus oxycliloride with ierric chloride have also been investigated.142
NaO ONa 'P-0--P /
" ) / I I I I \ H 0 0 ONa
( 8 ) /ONa
'P--P
NaO
/ll l l \ HO 0 0 ONa
A general structural theory of condensed phosphates has been developed for predicting the structures to be expected in various systems and for calculating the number of P-0-P links they contain. 143 Chromatographic separation of the products formed by the partial hydrolysis of Graham's salt has revealed the existence of ring phosphates higher than the tetra- metaphosphate ; the penta- 2nd possibly the hexa-metaphosphate have been identified and it appears probable that a continuous range oi even larger ring phosphates is also present.144 The thermal dehydration of alkali-metal dihydrogen monophosphates has been investigated and similar studies indicate that, with the exception of sodium trimetaphosphate Na,P30,, all the tri- and tetra-metaphosphates of lithium, sodium, potassium, and ammonium and their hydrates are thermally unstable; five types of thermal behaviour were recognized. 145 The first complete X-ray structural analysis of a fibrous colloidal metaphosphate has been carried out on rubidium metaphosphate, which was shown to consist of continuous chains of (PO,),n- which spiral round the b axis of the crystal with a repeated pattern every two PO, The crystal structures of Maddrell's salt (NaPO,), and of lithium and sodium polyarsenate (MASO,). are somewhat similar to this but differ in the orientation of the chains and their repeat-patterns.147
Phosphoric triamide OP(NH,), may be prepared by the reaction of phosphorus oxychloride with liquid ammonia ; the use of substituted oxy- chlorides leads to the alkylamides of ortho- and thio-phosphoric acids and to the amides of phosphoric acid esters OP(0Et) (NH&, etc.148 Similarly,
1313 W. L. Groeneveld, Rec. Trav. chim., 1956, 75, 594; V. Gutmann, ibid., p. 403; D. S. Payne, ibid., p. 620.
139 I. A. Sheka and B. A. Voitovich, Zhzw. neorg. Khim., 1956, 1, 964. 140 E. M. Larsen and L. J. Wittenberg, J . Amer. Chem. SOC., 1955, 77, 5850. 141 L. A. Nisel'son and B. N. Ivanov-Emin, Zhur. neorg. Khim., 1956, 1, 1766. 142 V. V. Dadape and M. R. A. Kao, J . Amer. Claem. SOC., 1955, 7'7, 6192. 143 J. R. Van Wazer and E. J . Griffith, ibid., p. 6140. 144 J. R. Van Wazer and E. Karl-Kroupa, ibid., 1956, 78, 1772; J . F. McCullough,
145 E. Thilo and H. Grunze, 2. u+?.org. Chem.. 1955, 281, 262, 284. 146 D. E. C. Corbridge, Acta Cryst., 1956, 9, 308. 1 4 7 K. Dornberger-Schiff, F. Liebau, and E. Thilo, ibid., 1955,8,752 ; F. Liebau, ibid.,
148 M. Goehring and K. Niedenzu, Chma. B r v , 1956, 89, 1768.
J. R. Van Wazer, and E. J . Griffith, ibid., p. 4528.
1951, 9, 811; W. Hilmer, ibid., p. 87.
KEP.-VOT.. 1.111 D
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st3 INORGANIC CHEMISTRY.
pyrophosphoryl chloride gives the tetra-amide of diphosphoric acid (NH,),PO*O*PO(NH,),. This is isotypic with the tetra-amide of imidodi- phosphoric acid (NH,),PO*NH~PO(NH,), which can be prepared from phosphoric triamide by splitting out ammonium chloride with hydrogen chloride : 2(NH2),P0 + HC1+ (NH,),PO*NH*PO(NH,), + NH,CI. Some penta-amide of di-imidotriphosphoric acid
(NH,),PO*NH*PO( NH,)*NH-PO( N H2) , is also formed.149 On the other hand, when phosphoric triamide reacts with phosphorus oxychloride the tetramer of orthophosphoric amide imide (9) may be obtained via the chloride intermediate : l50
3PO(NH,), + POCI, + P4H,oO4N,CI + 2NHdCl N H,
P,Hl0O4N,CI __t P4HI2O4N8
y 2 y 4 2 NaO, yNk!, ,ONa O=P-NH-P=O
I I 0 4 P o (10) HN NH
( 9 ) YH NH I O=P-NH-P=O
I I / ** NH2 NHz NaO
Sodium monoamidophosphate Na2P03NH2, when heated in vacuuiii at 210" for several days, lost ammonia -to give tetrasodium imidodiphosphate Na,(PO,*NH*PO,) which is isotypic with the pyrophosphate Na,P,O,. Further heating to 450" yielded sodium nitrilotriphosphate (Na,P0,),N.151 Similarly when sodium diamidophosphate was heated in vacuum to 160°, diamido-imidophosphates of general formula Na,P,O,,(NH) ,- I(NH,)2 (1 1) were formed where IZ = 2-6. Treatment of the products with sodium nitrite gave sodium imidophosphates of formula Na, + 2P1102n 2(NH), - ( lZ) .152 The reactions may be written as follows:
......... ONa ONa ONa I ............ ONa I .. ONa I I I '. I .*. ONa
H ~ N - P - N H . ~ + H ~ N ~ P-NH:;' + -.--H~N;- P - N H ~ - (n- I NH) + H ~ N - P ~ N H ~ P - N H .. - . .P-NH~ I t ........... . * I 1 . . . . . . . . * I 1 II II II
0 ( 1 1 ) 0 0 0 0
ONa ON a ONa ONa I I I 1
II II II I I 0 0 0 0 (12)
H~N-P-NH..*-.-P--NH2 + 2NaN02 + 2H20+ ZN2 4- NaO-P-NH*.*-** P-ONa
Contrary to assertions in the older literature i t now appears that hydrolysis of sodium trimetaphosphimate (10) tends to occur by replacement of the ring-NH groups by oxygen atoms ; chain imidophosphates are never present in large a m 0 ~ n t s . l ~ ~
R. Klement and L. Benek, 2. anorg. Chem., 1956, 287, 12. 149 M. Goehring and K. K. Niedenzu, Chem. Ber., 1956, 99, 1171; see also
1-50 M. Goehring and K. Niedenzu, Chem. Ber., 1956, 89, 1774. 151 R. Klement and G. Biberacher, 2. amrg. Chem., 1956, 283, 246 1 6 2 Idew, ibid., 1950, 285, 74. l53 A. Narath, F. H. Lohman, and 0. T. Quimby, J . Amer. Chem. Soc., 1956, 78,
4493.
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ADDISON AND GREENWOOD : MAlN GROUPS. 99
X-Ray analysis has shown that the compound KAs,O,I has a new type of layer structure with the following layer sequence parallel to the G axis : . . . I-2As-30-K-30-2As-I . . . ; the As-0 distance corresponds to covalent bonding.lM Arsenic(II1) selenide reacts with liquid ammonia to give a soluble metaselenoarsenite and an insoluble amidoselenide according to the equation As,Se, + 2NH, + NH,AsSe, + AsSeNH2, whereas the corre- sponding arsenic(II1) sulphide gives an imido-derivative : As,S, + 2NH, ----t As,S,NH + NH,HS.155
Two new antimony salts are described: Rb2SbBr5 and Rb,Sb,Br,,. The first is prepared by removing bromine vapour from solid Rb,SbBr,, and the second by adding bromine to Rb,Sb,Br,.156 Various derivatives of liexafluoro- and hexachloro-antimonic acids have been made. 15' Addition of chlorine to tristrifluoromethylantimony Sb(CF,), gives the compound (CF,),SbCl, which reacts with water to form a mono- and a di-hydrate; a solution of tristrifluoromethylantimonic acid H(CF,),Sb( OH),, which is unique in being the only known strong monobasic acid of antimony(v), can also be is01ated.l~~ Antimony pentachloride reacts with dialkyl sulphites, (RO),SO, to give C1,SbOR.157 Reaction with a solution of sulphur trioxide in sulphuryl chloride yields pyrosulphuryl chloride and the new compound Sb,CI,SO, which may be formulated as the salt (SbC14+)2S042-.159
X-Ray powder photographs show that " sodium metabismuthate '' has the ilmenite structure and is best described as sodium bismuth(v) trioxide. 160
Group V1.-The stereochemistry of the elements in Group VI has been reviewed.161 The Raman spectrum of the hydroxonium ion H,O+ is reported for the first time,lG2 and the ion is now recognized as a lattice component in several hydrated sulphates and phosphates of iron analogous to ferrous ammonium salts.lG3
Physicochemical measurements continue on the sulphuric acid system,164 and the work has been extended to solutions in disulphuric acid.165 A re- investigation of the system HN0,-H,SO,,nSO, establishes the identity of live compounds in the range n < 1 ; when n > 1 nitronium hydrogen tetra- sulphate is formed (N02,HS,013).166 With dioxan, sulphuric acid forms the compound H,S0,,C4H,02 which melts a t 100" and has a conductivity of 2 x lo-, ohm-l ~ r n . - l . l ~ ~ Two new incongruently melting compounds have
154 2. Galdecki, Roczniki Chem., 1956, 30, 355.
156 G. Brauer and Ti.-D. Schnell, ibid., 1956, 283, 49. 15' A. Meuwsen and H. Mogling, ibid., 1956, 285, 262. 158 H. J. Emeleus and J. H. Moss, ibid., 1956, 282, 24. 159 R. Appel, ibid., 1956, 285, 114. 160 B. Aurivillius, Acta Chem. Scand., 1955, 9, 1219. 161 S. C. Abrahams, Quart. Rev., 1956, 10, 407. 162 J. T. Mullhaupt and D. F. Hornig, J. Chem. Phys., 1956, 24, 169; see also D. J.
Millen and E. G. Vaal, J., 1956, 2913. N. V. Shishkin and Ye. A. Krogius, Zhur. neorg. Khim., 1956, 1, 1252; see also
F. Halla and E. van Tassel, Natzwwiss., 1956, 43, 80. 164 R. J. Gillespie and J. V. Oubridge, J., 1956, 80; R. Flowers, R. J. Gillespie, and
S. Wasif, ibid., p. 607; R. Flowers, R. J . Gillespie, and J. V. Oubridge, ibid., p. 1925; R. J. Gillespie and R. C. Passerini, ibid., p. 3850.
165 J. R. Brayford and P. A. H. Wyatt, Trans. Faraday Soc., 1956, 52, 642. lo6 V. A. Usol'tseva, Zhur. priklad. Khim., 1956, 29, 302, 306. 167 Ya. F. Mezhennyi, J . Gen. Chenz. (U.S.S.R.), 1956, 26, 397.
H. Behrens and L. Glasser, 2. anorg. Chenz., 1956, 282, 12.
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100 INORGANIC CHEMISTRY.
been detected in the binary system water-selenic acid : H2Se0,,2H,0, m. p. -24", and H2Se0,,6H,O, m. p. -68.4°.168 Thermal analysis of the system water-selenium trioxide also reveals two new compounds : H2Se,0,, m. p. 18.8", and H,Se3OIl melting incongruently with a peritectic temper- ature 169 of 25.4".
A single-crystal structure analysis of sodium dithionite Na,S,O, reveals that the anion consists of two SO,- groups joined by a very long S-S bond (2.39 A) ; the sodium ions are also in an unusual, approximately square, c o - ~ r d i n a t i o n . ~ ~ ~ A considerable amount of work is being published on the chemistry of the sulphanes H,S, and the chlorosulphanes S,C1, and many of the lower members of these series (n < 6) can be obtained reasonably pure.171
Fluorosulphites are prepared by the addition of gaseous sulphur dioxide to alkali-metal or tetra-alkylammonium fluorides, the reaction being more ready the larger the cation : M F + SO, MS0,F. The fluorosulphite ion, which is isoelectronic with the chlorate ion, is stable in an atmosphere of SO, up to 150" but above this temperature it reacts to give the corre- sponding fluorosulphate : 2MS0,F + SO, --+ ZMSO3F + S. Fluorine and chlorine convert the compounds into S0,F2 and SO,ClF, and a phase study of the system HF-SO, demonstrates the existence of the parent acid HSO,F, m. p. -84°.172 The amide of fluorosulphurous acid SO(NH,)F is obtained from ether solutions as the product of the reaction of ammonia with a large excess of thionyl fluoride; the volatile compound soon forms a solid yellow linear polymer [OS(NH,)F].. Primary amines tend to react analogously but the product OS(NHR)F readily splits off hydrogen fluoride to give thionyl imines OSNR ; secondary amines yield stable dialkylamides of fluorosulphurous acid OS(NR,)F.173
The generic relation of pyrosulphuryl fluoride S,05F, as the anhydride of fluorosulphuric acid HS0,F has a t last been established by using arsenic(v) oxide as a mild dehydrating agent; the reaction proceeds at 300" via the intermediate formation of a volatile arsenic fluorosulphonylfluoi-ide : 174
IOHSO3F + As206 __t 2AsF,(SO,F), + HzSO, + HZ0 ~AsF~(SO~F)~ - 3SaO6Fz + As,O,F,
Earlier work on the ammonolysis of pyrosulphuryl choride which had been interpreted on the basis of the reaction S,O,Cl, + 6NH, + 2NH,C1 + (NH4)2[S205(NH)2] could not be confirmed and the reaction is now formu- lated as 175 2SzOjCIz + I2NHS- 4NHdCI + (NH,)SO,NH, + SO,(NHZ)Z + NH,*SOg.N(NH4)*SO,NH4
168 G. Vuillard, Compt. rend., 1956, 242, 1326. 189 K. DostAl, COX Czech. Chem. Comm., 1955, 20, 1033; Chem. Listy, 1955, 49,
633 ; see also K. DostAl and M. Cernohorsky, ibid., 1956, 50, 702. 17O J. D. Dynitz, Acta Cryst., 1956, 9, 579. 171 F. Feller, W. Laue, and J. Kraemer, 2. a n o ~ g . Chem., 1955, 281, 151; F. FehQ
and G. Rempe, ibid., p. 161; F. Feh6r and L. Meyer, 2. Naturforsch., 1956, l lb , 605; F. FehCr and W. Laue, 2. anorg. Chem., 1956, 287, 45; H. P. Meissner, E. R. Conway, and H. S. Mickley, I n d . Eng. Chem., 1956, 48, 1347.
172 F. See1 and L. Riehl, 2. anorg. Chem., 1956, 282, 293. 173 M. Goehring and G. Voigt, Chem. Ber., 1956, 89, 1050. 174 E. Hayek, A. Aignesberger, and A. Engelbrecht, Monatsh., 1956, 86, 735. 175 R. Appel, G. Voigt, and E . H . Sadelr, Naturwiss., 1966, 43, 496.
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ADDISON AND GREENWOOD : MAIN GROUPS. 101
The last compound is the diammonium salt of a formerly unknown imido- sulphuric acid, and is also formed by the ammonolysis of trisulphuryl fluoride : 175
2SaOeFZ + IONH:, ZNH,SO,F + 2HF + NH,SO,NH, + SO,(NH,), + NH,*S02.N(NH,).SOa*NH,
On the other hand ammonolysis of trisulphuryl chloride appears to give NH,SO,NH,, SO,(NH,),, and the corresponding triammonium salt (NH4)JN (SO,),]. 17G Finally, NN'-dimethylsulphamidedisulphuric acid an- hydride (13) is completely ammonolysed by ammonia to give sulphamide, dimethylsulphamide, N-methylsulphamic acid, and amidosulphuric acid.17s All these experiments indicate that the S-0-S system is much less stable towards ammonlysis than the P-0-P grouping.
Sulphur trioxide reacts with cyanogen chloride CNCl to give three new compounds : N-carbonylsulphamyl chloride OC=N*SO,Cl, which hydrolyses
to CO,, NH,.SO,H, and HC1; the corresponding derivative of pyrosulphuric acid OC=N*SO*O*SO,Cl; and the cyclic compound (14).177 Thiazyl bromide (NSBr), reacts with potassium amide to give a yellow reactive solid K,N,S which may be considered as a derivative of sulphur di-imide S(NH),. From thiazyl chloride (NSCl), and mercuric iodide in liquid ammonia the corresponding salt HgN,S was prepared.17*
The chemistry of sulphur nitride and its derivatives has been revie~ed.17~ Disulphur dinitride can be obtained by the thermal decomposition of tetra- sulphur tetranitride under very carefully controlled conditions ; its structure is thought to be S=N-S=N.lG0 The formation of S,N,Cl from S,N, and acetyl chloride or sulphur chloride is ascribed to traces of free hydrogen chloride in the reagents.lG1 The thermal decomposition of SN,F, gives a mixture of sulphur tetrafluoride, nitrogen, and the colourless gas SNF which is the monomer of (SNF), mentioned in last year's Report (p. 117). Under milder conditions SN,F, disproportionates into SNF and SNF,.l82 The last compound, which is the most stable of the sulphur-nitrogen fluorides m-ay also be prepared by the reaction of a gaseous mixture of SNF and SN,F2 with silver difluoride; the sulphur is in the +4 oxidation state and the structure of the compound is therefore F,S=NF in contrast with thio- phosphoryl fluoride which is S=PF3.ls3
+
176 H.-A. Lehmann and G. Ladwig, 2. anorg. Chem., 1956, 284, 1. 1 7 7 R. Graf, Chern. Ber., 1956, 89, 1 0 7 1 . 178 W. Berg, M. Goehring, and H. Malz, 2. anorg. Chem., 1956, 283, 13. 179 M. Goehring, Quart. Rev., 1956, 10, 437. 160 M. Goehring and D. Voigt, Z . anorg. Chem., 1956, 285, 181. 181 A. G. MacDiarmid, J . Amer. Chem. Soc., 1956, 78, 3871. 182 0. Glemser and H. Haeseler, 2. anorg. Chem., 1956, 287, 54. 18s 0. Glemser and H. Schroder, ibid., 1966, 284, 97.
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102 INORGANIC CHEMISTKY.
The tetrafluorides of sulphur and selenium form solid 1 : 1 addition compounds with boron trifluoride melting at 80" and 46", and there are in- dications that tellurium tetrafluoride reacts similarly. Addition compounds of these tetrafluorides with arsenic and antimony pentafluorides are also described.184 A convenient preparation of tellurium tetrafluoride from tellurium dioxide and selenium tetrafluoride is reported.lS5 The fluorination of tellurium has been studied under a variety of conditions ; TeF,, TeF,, and Te,F,, were obtained. In the presence of tellurium dioxide a tellurium oxyfluoride Te302F14 is also obtained which may be formulated TeF5*O*TeF4*O*TeF5 ; this compound has a ratio of molecular weight to boiling point of 1.67 and is therefore even more volatile for its molecular weight than Te,F,,, which previously had the highest value for this ratio (1.36) of any known compound. Another product of the reaction appears to be Te,05F2,, i.e., TeF5[O*TeF4],*O~TeF5.1s6
The extraction of polonium(1v) from nitric acid into ethers depends on the presence of reducing agents such as SO,, H20,, N2H4, NH20H, and organic peroxides; in the absence of these agents negligible extraction occurs in the dark.187 The preparation of a basic sulphate of polonium 2P002,S03, a basic selenate 2PoO,,SeO,, and a less stable disulphate Po(SO4), is described, and these reflect the increased basicity of polonium compared with its lighter congeners. la8 Polonium tetraiodide has been prepared by direct reaction of the elements at 40°/1 mm., by the reaction of PoO, and HI at 200", and by the. reaction of the dioxide with aqueous hydriodic acid. Addition of czsium iodide gives a black precipitate of the hexaiodopolonate Cs2PoI6 which is isostructural with C S , T ~ I , . ~ ~ ~ The potential of the polonium electrode (polonium deposited on gold in contact with a solution of Porv in N-HNO,) against a saturated calomel electrode is E, = -/-0.?'6 v.lgo
Group VII.-The purification of hydrogen fluoride in an apparatus con- structed of Fluorethene plastic leads to samples of considerably lower conductivity than previously obtained; the lowest value was 1.6 x ohm-l crn.-l at 0" compared with the accepted vahe of 1-4 x at - 15'.191 Antimony pentafluoride behaves as an acid in hydrogen fluoride (SbF, + 2HF -e H2Ft + SbF,-) and the mobilities of these ions, together with those from the strong electrolytes NaF, KF, and NaSbF, have been deter- mined at infinite dilution. The low value for the hydrogen ion eliminates the possibility of a chain mechanism involving this species but the rather large mobility of the fluoride ion may indicate an abnormal process for this ion.lg2 The fluorides of titanium, niobium, and tantalum are good electron acceptors in hydrogen fluoride in the sense that they favour the reaction m-xylene +
N. Bartlett and P. L. Robinson, Chew. and Ind. , 1956, 1352. lE5 R. Campbelland P. L. Robinson, J. , 1956, 785. 186 Idem, ibid., p. 3454; see also G. Hetherington and P. L. Robinson, ihid., I>. 3682
187 J. Danon and A. A. L. Zamith, Nature, 1956, 177, 746. 188 K. W. Bagnalland J. H. Freeman, J., 1956, 4579. 189 K. W. Bagnall, R. W. M. D'Eye, and J. H. Freeman, ibid., p. 3385; see also
100 K. W. Bagnall and J. H. Freeman, J., 1956, 2770. 191 M. E. Runner, G. Balog, and M. Kilpatrick, J . Amer. Chem. Soc., 1956, 78, 5183. 182 M. Kilpatrick and T. J . Lewis, ibid., p. 5186.
for viscosity of Te,F,,.
0. M. JankoviC, Bull. Inst. NucZear Sci. Boris Kidrich, 1956, 6, 143.
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;\I>l)ISON A N D GREENWOOL) MAIN GKOUPS. 103
H F + (m-xylene H)+ + F- by removing the fluoride ions according to reactions like F- -t NbF, + NbF,-. Phosphorus pentafluoride is less effective, and the fluorides of Ba, Si, PbII, SbIII, BPI1, ZrIV, Cr1IT, WF*, and Zn are inactive.lg3
Hydrogen chloride forms a hexahydrate, m. p. - 70.0", in addition to the known di- and tri-hydrates.lg4 The electron-donor capacity of x orbitals in unsaturated hydrocarbons has been studied by using hydrogen chloride as a convenient, small, acceptor molecule. Phase diagrams with olefins show the presence of low-melting addition compounds with one and two mols. of acid, acetylenes form compounds at these ratios and also with four mols. of acid, whereas aromatic hydrocarbons tend to form 1 : 1 compounds only.lg5
The thermal decomposition of dichlorine hexaoxide in the presence of fluorine gives a 70% yield of chloryl fluoride C10,F. The hexaoxide de- composes according to the equations C1206 + ZlO, 2C10, + 0, ; neither Cl,06 nor ClO, reacts with fluorine but the dioxide does and indeed chloryl fluoride may be prepared by the direct reaction of undiluted chlorine dioxide and fluorine. lg6 Perchloryl fluoride ClO,F, which was recently obtained in small yields either by electrolysis of perchlorates in H F or by direct fluorination of chlorates, has now been prepared in 67% yield by the reaction of perchlorates with fluorosulphuric acid. lg7 It is a colourless, inert, thermally stable gas (m. p. -146", b. p. -47.5") in contrast to C10,F and ClO,OF which are explosive or highly reactive. Perchloryl fluoride reacts slowly with ammonia to give ammonium imidoperchlorate : C10,F + 3NH, + NH,F -t NH,NHC10,.lg8 Analysis of the vibration spectrum and rotational fine structure of ClO,F indicates a central C1 atom with the 0 atoms at the base and the F atom at the apes of a trigonal pyramid, FClO,, but the absence of microwave absorption suggests that the molecular dipole is very small and probably much less than 0.09 D.lg9
Fluorine fluorosulphonate, prepared by the action of fluorine on sulphur trioxide in the presence of silver difluoride, is a reactive oxidizing agent, m. p. --158.5", b. p. -31.3"; its chemical reactions and infrared spectrum confirm the structure S02F*OF.200 The catalytic fluorination of thionyl fluoride over silver difluoride yields thionyl tetrafluoride F,S=O (m. p. -99.6", b. p. -49-0") and pentafluorosulphur hypofluorite F,S-OF (m. p. -86-0", b. p. -335.0"); the structures were deduced from chemical reactions and infrared spectra,201 and confirmed by nuclear magnetic resonance.202
The electric dipole moment of gaseous bromine trifluoride suggests a planar T-shaped molecule similar to that found for chlorine trifluoride.,N
193 D. A. McCaulay, W. S. Higley, and A. P. Lien, J. Amer. Chem. SOC., 1956, 78,3009. 194 G. Vuillard, Compt. rend., 1955, 241, 1308. 195 D. Cook, Y. Lupien, and W. G. Schneider, Canad. J . Chem., 1966, 34, 955, 964. 1913 A. J. Arvia, W. H. Basualdo, and H. J. Schumacher, 2. anorg. Chew., 1056, 286,
197 G. Barth-Wehrenalp, J . Inorg. Nuclear Chem., 1956, 2, 266. 198 A. Engelbrecht and H. Atzwanger, ibid., p. 348. 199 R. P. Madden and W. S. Benedict, J . Chem. Phys., 1956, 25, 594; D. R. Lide
and D. E. Mann. ibid., p. 595. 200 F. B. Dudley, G. H. Cady, and D. F. Eggers, J . Amer. Chem. SOC., 1956, 78, 290. 201 Idem, ibid., p. 1553. 202 F. B. Dudley, J. N. Shoolery, and G. H. Cady, ibid., p. 568. tos M. T. Rogers, R . D. P r i i e t t , and J. L. Speirs, ;bid., 1955, 77, 5280.
58; see also J. E. Sicre and H. J. Schumacher, ibid., p. 232.
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104 INORGANIC CHEMISTRY.
There are two congruently melting compounds in the system bromine tri- fluoride-antimony pentafluoride ; BrF,,SbF,, m. p. 129.8", and BrF3,3SbF5, m. p. 33.5" ; and also two incongruently melting compounds, 3BrF,,SbF5, m. p. -16.3", and 3BrF,,2SbF5, m. p. 3043".204 An X-ray crystal-structure determination has shown that the tetrafluorobromate ion in KBrF, is tetra- hedral 205 in contrast to the tetrachloroiodate ion in KICl, which is planar. The vapour pressures of the addition compounds of bromine trifluoride with potassium bromide and antimony pentabromide (KBrF, and BrF,,SbF,) have been measured up to 350" and are of such a magnitude that the compounds can be used for high-temperature fluorinations in closed reaction vessels even up to 500°.206 The electric dipole moments of bromine pentafluoride 207 and iodine pentafluoride 203 are consistent with a square-based-pyramidal struc- ture and exclude trigonal-bipyramidal and plane-pentagonal symmetries. The phase diagrams of the systems bromine pentafluoride-hydrogen fluoride 208 and iodine pentafluoride-hydrogen fluoride 209 each show a single eutectic; there is no evidence of compound formation.
The crystal structure of x-iodine monochloride involves ICl molecules in two non-equivalent sets; these molecules, of bond length 2.37 and 2.44 A respectively, are arranged in puckered zigzag chains with strong interaction between the molecules in individual chains but with normal van der Waals distances between the chains.210 A detailed study of the crystal structures of the addition compounds of iodine monochloride with pyridine 211 and dioxan has shown that the N-I-C1 bond in Py,ICl and the 0-I-C1 bond in C,I-I8O2,2ICl are both linear and non-ionic By contrast, $-chlorobenzene iododichloride C1*C6H,*ICI, has a linear Cl-I-Cl group at right-angles to the C-I bond, the whole molecule being planar. The structure is allied to that of benzene iododichloride except that in this compound the ICl, group is also at right-angles to the plane of the benzene ring.213 (It may be noted that these two iododichlorides together with chlorine trifluoride and bromine trifluoride constitute the four known examples of T-shaped covalent bond angles so that chlorine, bromine, and iodine can all adopt this symmetry.)
The cryst a1 structure of t etraeth ylammonium hept aiodide Et ,N I is built up of I,- ions and I, molecules with large holes for the Et,N+ cations; the compound therefore is best written as Et,N+I,-,212; there is no indic- ation of an I,- i0n.214 The structure of tetramethylammonium enneaiodide
204 J. Fjscher, R. Liimatainen, and J. Bingle, J . Amer. Chenz. Soc., 1956, 78, 5848. 805 S. Siegel, Acta Cryst . , 1956. 9. 493. 208 I. Sheft, A. F. Martin, and J. J . Kstz, J . Amer. Chem. Soc., 1956, 78, 1557. 807 M. T. Rogers, R. D. Pruett, H. B. Thompson, and J. L. Speirs, ibid., p. 44;
208 M. T. Rogers, J. L. Speirs, and M. B. Panish, J . Amer. Chenz. SOL, 1956, 78,
209 M. T. Rogers, J . L. Speirs, M. B. Panish, and H. B. Thompson, ibid., p. 936;
210 K. H. Boswijk, J. van der Heide, A. Vos, and E. H. Wiebenga, Acts Cryst., 1956,
2 1 1 0. Hassel and C. Rsmming, Acla Chevz. Scand., 1956, 10, 696. 212 0. Hassel and J . Hvoslef, ibid., p. 138. 213 D. A. Bekoe and R. Hulme, Nature, 1956, 177, 1230. 214 E. E. Havinga and E. H. Wiebenga, PYOC. k . ned. Akad. Wetenschafi., 1055, 58, B,
see also M. T. Rogers and J. L. Speirs, J . Phys. Chem., 1956, 60, 1462.
3288.
see also G. Hetherington and P. L. Robinson, J . , 1956, 3681.
9, 274.
412.
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ADDISON AND GREENWOOD : THE TRANSITION ELEMENTS. 105
Me,NI, is more complicated. It consists of planes of densely packed iodine atoms which contain 5/9ths of the iodine atoms in the compound and within which there is some justification for singling out 1,- ions similar to but less symmetrical than, the V-shaped ions in h'Ie,NI,. Between these planes, which are 9.1 apart, lie Me,N+ cations each surrounded by six I, molecules ; these molecules also lie between the main planes, normal to them and weakly associated with them. Except for the I, molecules between the planes, all 1-1 distances are considerably longer than in I, and are comparable with those found in 13-, 15-, and 182-.215
3. THE TRANSITION ELEMENTS.
A large proportion of the work published during the year on the chemistry of the transition elements has been concerned with complexes. Work which illustrates the structure or general properties of particular types of complex is correlated under the heading " Complexes." The remaining chemistry of the transition elements is then discussed systematically ; these sections contain references to complexes which are more directly concerned with the chemistry of the particular elements. The paramagnetic resonance of crystalline solids containing ions of the transition groups has been reviewed.216 The proceedings of the International Conference on Co-ordination Com- pounds (Amsterdam, 1955),217 and a symposium on the chemistry of complex compounds,218 have been published. \V. Klemm has reviewed the present position regarding valency ranges in the transition elements, particularly the abnormal valencies shown in their oxygen and fluorine c0mplexes.~19
Complexes.-Import ant advances have been made in the elucidation of the mechanism of substitution in octahedral (mainly CoIII) complexes, and the related stereochemical changes."O They involve kinetic studies which lie outside the scope of this Section. The stability and the spectra of complexes of transition metal cations have also been discussed,221 with emphasis on the application of crystal field theories.z22
The well-known reducing and catalytic properties of a solution of iron pentacarbonyl in aqueous hydroxide solutions are interpreted satisfactorily on
W. J. James, R. J. Ilach, D. French, and R. E. Rundle, Acla Cryst., 1955, 8,
216 K. D. Bowers and J. Owen, Reports Progr. Phys., 1955, 18, 304; see also Discuss.
217 Rec. Trav. chim., 1956, 75, 557-924. 218 Chem. Weekblad, 1956, 52, 193. 219 W. Klemm, Bull. SOC. chim. France, 1956, 1325. 220 S. Akperger and C. K. Ingold, J., 1956, 2862; F. Basolo, W. R. Matoush, and
R. G. Pearson, J . Amer . Chem. SOC., 1956, 78, 4883; R. K. Murmann and H. Taube, ibid., p. 4886; A. W. Adamson and F. Basolo, Acta Chena. Scand., 1955, 9, 1261 ; and refs. therein.
814.
Faraday Soc., 1955, 19.
221 H. Irving and H. Rossotti, ibid., p. 72. 222 C. K. Jm-gensen, ibid., p. 887; R. J. P. Williams, J . , 1956, 8 ; P. George, D. S .
McClure, J . S. Griffith, and L. E. Orgel, J . Chem. Phys., 1956, 24, 1269; C. J. Ballhausen, Rec. Trav. chim., 1956, 75, 666; and refs. therein.
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106 INORGANIC CHEMISTRY.
the basis of an intermediate dimeric ion (15) formed from two [Fe(CO),H]- ions which is oxidised to ion (16) : 223
(15) (16)
Dirhenium decacarbonyl undergoes a similar reaction : 224
1 K[ (OC),R\;/Re(CO), Lo\ R*2(CO)Io + 3KOH + H 2 0 + CO + K2CO3-t 2H1
( 1 7 )
The compound (17) is diamagnetic, each sexaco-ordinate Re atom maintain- ing its inert-gas configuration. The same product is formed from the carbonyl chloride :
Re,(CO),O,HK + 2KCI + 2CO + H,O
and with thiophenol the carbonyl chloride gives the non-electrolyte 2Re(CO),CI + 3KOH
ll(CO)4Re(S'C6H5)212* The position of the hydrogen atom in cobalt carbonyl hydride has been - -
further examined from its infrared spectrum. In the absence of an 0-H stretching vibration, the spectrum is consistent with a model in which the hydrogen atom bridges three CO groups; its covalent bonding to the CO groups is stronger than to the Co atom.225
The compound Ru(CO),I, has high stability and low vapour pressure, in marked contrast to the iron compound.226 This is consistent with a halogen- bridged polymeric structure (18) in which each Ru atom may also achieve inert-gas configuration.
The chemistry of mixed complexes containing isoelectronic groups has been developed. Nitrosylcyano-complexes of iron and nickel are known, and the corresponding cobalt complexes now isolated are correlated as follows : 227
KCN HCN [Co(NH,),NO]CI, __t K3[Co(CN),NO] ___t [Co(CN)dS- + $NzO
In the pentammino-complex the NO group has entered the complex as NO- ; the lower formal valency of the cobalt resulting from electron distribution to give NO+ is revealed by the reduction to nitrous oxide on replacement of the NO group. Again,
KCN Co(CO),NO __t [Co(CN)(CO),(NO)]- --j- Co(CO),NO + [Co(CN),(CO)(NO)]-'
CN- and [CO(CN),(CO)(NO)]~- __+ [Co(CN)3NOIS-
which is directly analogous to the carbonyl nitrosyl. 22s H. W. Sternberg, R. Markby, and I. Wender, J . Anzer. Chem. SOC., 1956, 78,
224 W. Hieber and L. Schuster, 2. anorg. Chem., 1956, 285, 205. 226 W. F. Edgell, C. Magee, and G. Gallup, J . Amer. Chem. SOC., 1956, 78, 4185,
2Z8 R. J. Irving, J., 1956, 2879. 227 R. Nast and M. Rohmer, 2. anorg. Chem., 1956, 285, 271.
5704.
4188; see also F. A. Cotton and G. Wilkinson, Chem. and Ind., 1956, 1305.
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A1)I)ISON ANI) GREENWOOD THE TRANSITION ELEMENTS. 107
A number of derivatives of iron and cobalt nitrosyl carbonyls with phosphorus, arsenic, and antimony alkyls and aryls are described.228 They include Co( NO) (CO) (PPh,) ,, Co (NO) (CO) , [As (C,H,Cl) J, Fe (NO),( PPh,),, and Fe(NO),[P(OPh),],, and a carbonyl derivative is obtained by the reaction 229
Hs[CO(CO),I~ + 2PPh3 HdCo(C0)3(PPhs)l2
isocyanides give 1 : 1 replacement of the CO group in carbonyls. With iron pentacarbonyl
CIH,-NC CHs.NC Fe(CO)5 - Fe( CO)4,C2H5NC ___t Fe(CO)3C2H5NCCH3*NC
This class of compound has been ~urveyed.2~0 Reaction of rhodium tri- chloride with RNC (R = tolyl, 9-chlorophenyl, methoxyphenyl) gives compounds of formula [(RNC),Rh]Cl in which the Rh atom is formally univalent .231
. The chemistry of metal acetylide complexes has been extended to include In liquid ammonia, the compounds analogous to ferro- and ferri-cyanides.
following reaction occurs :
6MCECR + Fe(SCN)?,4NH3
(where M = K, Na and R = H, Me, Ph). in liquid ammonia
M4[Fe(C-CR),] + ZMSCN + 4NH3
On reaction with gaseous oxygen
and the FeIII product can be reduced again by reaction with a solution of potassium in liquid ammonia.232 An analogous series of CoII and COTIT
complexes has been prepared.2a The trans-directing effect in platinous complexes has been further
examined. The elimination of groups in the trans position is attributed to the high double-bonding capacity of the directing ligand, and occurs by an SN2 mechanism. This is supported by the infrared spectra of a series of square planar complexes.234 An electronic interpretation of the lability of groups trans to the double-bonding ligand has been given which involves a distorted bipyramidal structure for the transition state.235 Advantage has been taken
228 M. Malatesta and A. Araneo, -4Iti Accad. naz. Lincei, lie9id. Classc Sci. j s . Inat.
229 W. Hieber and R. Breu, Angew. Chem., 1956, 68, 679. 230 W. Hieber and D. von Pigenot, Chem. Ber., 1956, 89, 610, 616. 231 L. Malatesta and L. Vallarino, J., 1956, 1867. 232 R. Nast and F. Urban, 2. anorg. Chem., 1956, 287, 17 . 233 R. Nast and H. Lewinsky. ibid., 1956, 282, 210. 234 J. Chatt, L. A. Duncanson. and L. M. Venanzi, J. , 1955, 4456, 4461 ; see also
D. B. Powell, J., 1956,4495; 0. Y . Zvyagintsev and Y. F. Karandasheva, Doklady Akad. Nauk, S.S.S.R., 1956, 108, 477.
235 Id. E. Orgel, J . T w o ~ g . Nuclear Chem., 1956, 2, 137.
nnt., 1956, 20, 365.
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108 INORGANIC CHEMISTRY.
of the labile nature of the group trans to an ethylene molecule to determine equilibrium constants for the reactions
and trans-C,H,,H20PtC12 + am + tmns-C,H,,amPtCl, + H20
and thus the relative tendencies of a series of simple amines (am) to co- ordinate with the meta1.236 The possibility that the cyclobutadiene molecule can be stabilised by combination with a transition-metal ion has been examined by molecular-orbital theory.237 An interesting olefin complex [C,H,,RhCl], is formed by reaction of rhodium trichloride with cycloocta- 1 : 5-diene.238 When treated with an amine (am) it gives the mononuclear planar complex C8H1,,Rh amC1, and on treatment
C2H,PtC13- + am trans-C,H,,amPtCl, + C1-
It has structure (19).
OH
with cyclopentadienylsodium gives the novel derivative C,H,,,RhC,H, (m. p. 108'). Acetylene complexes of some transition metals have been prepared, but structures are uncertain. The infrared spectrum of the known compound Fe,C,,H,O,, prepared by reaction of acetylene with iron carbonyl hydricle, indicates that it is binuclear (80) and closely related to the nona- carbonyl. The two acidic hydrogen atoms are attached directly to oxygen atoms.239 A wide range of substituted acetylenes RCGCR, undergo the reaction
RC-CR, + CO,(CO), (CO)~CO*RC-CR,*CO(CO)~ + 2CO
but the multiplicity of the bonds connecting the two Co atoms through the acetylene has not yet been ascertained.240 The complex K[Cl3Pt ,Me,( 0H)C-CrC*C (OH) Me,] has been described.241
There have been considerable developments in the chemistry of metal- cyclopentadiene complexes during the year, and many compounds are now classified according to whether they form sandwich-type bonds, ionic bonds between metal and C,H,- ions, or localised metal-carbon bonds. The two well-known approaches to the structure of ferrocene-type compounds, i.e., the single bond concept and that involving multiple bonding (and the attain- ment by the metal of the inert-gas structure), have been compared and are not necessarily irreconcilable ; 242 in the series (C,H,)V(CO),, (C,H,)Mn(CO),,
296 J. Chatt and G. A. Gamlen, J., 1956, 2371. 237 H. C. Longuet-Higgins and L. E. Orgel, ibid., p. 1969. 238 J. Chatt and L. M. Venanzi, Nature, 1956, 177, 852. 239 H. W. Sternberg, R. A. Friedel, R. Markby, and I. Wender, J . Amer. Chem. SOC.,
240 H. Greenfield, H. W. Sternberg, R. A. Friedel, J. H. Wotiz, R. Markby, and
2 4 1 S. V. Bukhovets, Izvest. Sekt. Platiny, 1955, No. 29, 55, 242 J. W. Linnett, Trans. Faraday Soc., 1956, 52, 904.
1956, 78, 3621.
I. Wender, ibid., p. 120.
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ADDISON AND GREENWOOD : THE TRANSITION ELEMENTS. 109
(C,H,)Co(CO),, C,H,NiNO there is agreement that only the latter concept is tenable.243 A detailed crystallographic examination of ferrocene, (x-C,H,),Fe, gives the Fe-C distance, d(Fe-C), as 2.045 & 0.01 0.02 A; electron-diffraction studies give d(Fe-C) 2-03 & 0.02 and d(C-C) 1.43 & 0.03 H1.245 Crystallographic data are also available for dicycZopentadienylchromium( 11) 246 and for molybdenum, tungsten, and iron cyclopentadienyl ~a rbony l s .~*~
More metals have been added to the list of those forming cyclopentadienyl complexes; the usual method of preparation is by reaction of sodium pentadienide with a salt (e.g., halide) of the metal in an organic solvent (e.g., tetrahydrofuran or dimethylformamide). Scandium, yttrium, lanthan- um, and the lanthanide elements Ce, Pr, Nd, Sm, Gd, Dy, Er, and Yb give crystalline solids of formula M(C5H5), ; the metal-to-ring bonds are ionic in nature.248 Titanium dichloride gives dark green crystals of (x-C,H,),Ti, a ferrocene-type compound.249 The manganese compound (C5H5),Mn shows ionic bonding, in contrast to the sandwich structure of neighbouring elements. This is related to the extra stability of the &In2+ ion, with its singly occupied 3d orbitals.250 The Cu+ ion might be expected to form sandwich-bond compounds of the type C5H5CuR, isoelectronic with C,H,NiNO, but the infrared spectrum of the compound C5H5CuPEt, suggests that it should be formulated with a localised metal-carbon bond,251 as is the case with the mercury compound (C,H,),Hg. The dipole moments of the tin252 and lead 253 compounds (C,H,),Sn and (C,H,),Pb, 1-01 D and 1.63 D, indicate that they are also normal organometallic compounds.
Many derivatives of simple cyclopentadienyl complexes have been prepared.
and d(C-C) 1.403
Dicyclopentadienyliron dicarbonyl is obtained by the reactions Bra C,H,Na
(C,H,),Fe,( CO), __t 2C,H,Fe(CO),Br ___+_ C,H6Fe( C0)2C5H6
Only one C,H, group is symmetrically bonded to the iron atom, and the compound is useful in the synthesis of unsymmetrically substituted ferrocene derivatives2S4 The carbonyl hydrides C5H5M(C0),H (where A1 = Cr, Mo, W) have been prepared. The tungsten compound (m. p. 66') is the most stable.255 They represent fission of the dimeric complex by hydrogen, and are related in the same way as are the simple carbonyl and carbonyl hydride of cobalt. The hydrides readily give salts of the anion [C,H,M(CO),]-. Two new nitrosyl derivatives C5H5Cr(NO),C1 and (C,H,),Mn,(NO), have been described.25G The former has a sandwich-bonded cyclopentadienyl
243 L. E. Orgel, J . Inorg. Nuclear Chern., 1956, 2, 315. 244 J. D. Dunitz, L. E. Orgel, and A. Rich, Acta Cryst., 1956, 9, 373. 245 E. A. Seibold and L. E. Sutton, J . Chem. Phys., 1955, 23, 1967. 246 E. Weiss and E. 0. Fischer, 2. anorg. Chem., 1956, 284, 69. 247 F. C. Wilson and D. P. Shoemaker, Naturwiss., 1956, 43, 57. Z48 J. hl. Birmingham and G. Wilkinson, J . Awzer. Chem. Soc., 1956, 78, 42. 249 A. K. Fischer and G. Wilkinson, J . Inorg. Nuclear Chem., 1956, 2, 149. 250 G. Wilkinson, F. A. Cotton, and J. M. Birmingham, ibid., p. 95. 2 5 1 G. Wilkinson and T. S. Piper, ibid., p. 32. 252 E. 0. Fischer and H. Grubert, 2. Naturforsch., 1956, l l b , 423. 253 Idenz, 2. anorg. Chern., 1956, 286, 237. 254 B. F. Hallam and P. L. Pauson, J., 1956, 3030. 255 E. 0. Fischer, W. Hafner, and H. 0. Stahl, 2. anorg. Chem., 1956, 282, 47. 2 5 6 T. S. Piper and G. Wilkinson, J . Inorg. NucZear Chem., 1966, 2, 38, 136.
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110 INORGANIC CHEMISTRY.
group, with zero-valent chromium. Structure (21) whicli is suggested for the latter compound involves the use of nitric oxide as a bridging group. Reaction of (21) with sulphur in carbon disulphide gives a disulphur deriv- ative (C,H,)Mn(NO)S, ; 257 this may represent a cyclopentadienyl derivative of a Roussin-type salt (Z), with possible polymerisation by linkage through sulphur at oms.
(23) (21) (rl2)
Whilst metal-to-carbon CJ bonds are unstable for most transition elements, the presence of a x-cyclopentadienyl ring on the metal so changes the orbitals that stable metal-carbon c bonds can be formed. Thus by reaction of x-C,H,Cr( NO),I with Grignard reagents, x-C5HgMo(C0),H with diazomethane, or x-C,H,Fe(CO),Na with alkyl or aryl halides, a number of derivatives of general type x-C,H,M(CO),(NO),R have been isolated in which the alkyl or aryl group R is bonded directly to the An analogous silyl-iron compound x-CSH,Fe(CO),SiMe, has an Fe-Si G bond.259
cycZoPentadienylchromium-acetylacetone bromide (23) is novel in that a cyclopentadienyl group is bonded to a transition metal which is also part of a chelate
Uranium tetrachloride reacts with the sodium derivative of cyclopenta- diene to give the monochloride (x-C,H,),UC1.261 This compound does not react with ferrous chloride in tetrahydrofuran and the metal-to-ring bonds are therefore not electrostatic. The compound is formulated [(C,H,),U] U-, the cation having three coplanar sandwich-type bonds a t angles of 120". Thorium forms cyclopentadienyl-metal halides analogous to those of titanium and zirconium.261 Platinum forms a compound (C,H6),PtC1,, but lack of a characteristic double-bond frequency in the infrared spectrum indicates that there may be cross-bonding between the two C,H, molecules.262
The isolation of dibenzenechromium(O), (C6H,),Cr,263 in which the electronic configuration of the chromium atom is the same as that of the iron atom in ferrocene, is of outstanding importance since it indicates that the orbitals of suitable transition metals can be filled with all the x-electrons of an aromatic system up to the configuration of the next inert gas. I t is prepared by heating together anhydrous chromic chloride, aluminium powder, aluminium chloride, and benzene. Hydrolysis of the product gives the salt [Cr(C,H6)2]fC1-, which is reduced by sodium dithionite to brown-
257 T. s. Piper and G. Wilkinson, J . Amer. Chem. Soc., 1956, 78, 900. 258 Idem, J . Iizorg. Nuclear Chem., 1956, 3, 104. 259 T. S . Piper, D. Lemal, and G. Wilkinson, Natuvwiss., 1956, 43, 129. 260 J. C. Thomas, Chena. and Ind., 1956, 1388. 2 6 1 L. T. Reynolds and G. Wilkinson, J . Inorg. Nuclear Chem., 1956, 2, 246. 262 J. R. Doyle and H. B. Jonassen, J . Amer. Chem. soc., 1966, 78, 3965. 263 E. 0. Fischer and W. Hafner, 2. Naturforsch., 1966, lob, 665.
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ADDISON AND GREENWOOD THE TRANSITION ELEMENTS. 11 1
black diamagnetic crystals of dibenzenechromium (m. p. 284") which de- compose at 300" to metallic chromium and benzene.264 Crystallographic examination shows the molecule to be centrosymmetrical, with parallel rings.265 Compounds containing toluene, &-xylene, tetralin, mesitylene, and hexamethylbenzene in place of benzene have also been prepared.265 A similar method with molybdenum pentachloride gives dibenzenemolybdenum(0) which is also diamagnetic and has the " doppelkegel structure.'' 266 Re- action with diphenyl gives bisdiphenylchromium iodide [Cr(C6H5*C6H5)2]I,26i the magnetic properties and spectrum of which are identical with those of " tetraphenyl chromium iodide " prepared by Hein in 1919.268 Reactions typical of the ferrocinium ion occur also with the Cr(C6H6),' cation; thus dibenzenechromium cyclopentadienylchromium tricarbonyl is found to be the ionic compound [Cr(C6H6)~+[C5H5Cr(C0)3]- analogous to the cyclo- pentadienyl compound already known.269 The product of the reaction
AICI, FeBr, + 2C,H,Me, + [Fe(C,H,Me3),]'+ + 2Br -
is a niesitylene-iron(I1) cation which is isoelectronic with the neutral chromium(0)-mesitylene compound, and has the same structure.2i0
The Scandium Group and Lanthanides.-By combination of fractional hydroxide and carbonate precipitation with chromatographic separation on y-A1203, pure yttrium oxide (magnetic susceptibility -0.197 x 10-6/g.) containing < 0.002% of other lanthanides has been prepared.271 The efficiency of scandium separations has been tested by using the 46Sc isotope; precipitation as the potassium double fluoride, ammonium double tartrate, or by disodium hydrogen phosphate is more efficient than precipitation as hydroxide, oxalate, or pyrophosphate. Solvent extraction of scandium oxine chelate by chloroform can be made quantitative in one operation.272 Conditions of cathode potential and pH have been defined for separation of samarium from gadolinium by electrolysis of the citrate complexes with a lithium amalgam cathode, which is superior to sodium amalgam for this purpose.273 The stability constants of lanthanide complexes with hydroxy- ethylethylenediaminetriacetic acid show little variation from samarium to erbium ; 274 separations on cation-exchange resins with 2-hydroxyethylimino- diacetic acid complexes are also described.275 Weight-temperature curves for thermal decomposition of the nitrates M(N03),,6H20 give the following temperatures for complete conversion into oxide : La 780"; Ce 450"; Pr 505" ; Nd 830" ; Sm 750".276
Lanthanum, cerium, praseodymium, and neodymium behave similarly 264 E. 0. Fischer and W. Hafner, 2. anorg. Chem., 1956, 286, 146. 265 E. Weiss and E. 0. Fischer, ibid., p. 142. 266 E. 0. Fischer and H. 0. Stahl, Chem. B e y . , 1956, 89, 1806. 267 E. 0. Fischer and D. Seus, ibid., p. 1809; I?. Hein, ibid., p. 1816. 268 Idem, Bey., 1919, 52, 195. 269 E. 0. Fischer and H. P. Kogler, Angew. Chem., 1956, 68, 462. 270 E. 0. Fischer and R. Bottcher, Chem Bey., 1956, 89, 2397. 2 7 1 W. Fischer and K. E. Niemann, Z. anorg. Chem., 1956, 283, 96. 272 R. C. Vickery, ./., 1956, 3113. 173 E. I. Onstott, J . Anzer. Chem. SOC., 1956, 78, 2070. 274 F. H. Spedding, J . E. Powell, and E. J . Wheelwright, ibid., p. 34. 2 7 5 L. Wolf and J. Massonne, J . prakt. Chenz., 1956, 3, 178. 2713 W. W. Wendlandt, Analyt. Chinz. Acfa, 1956, 15, 435.
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112 IN ORGANIC CHEMISTRY.
in their systems with hydrogen. For compositions between &I and MH, two solid phases (metal and hydride) exist ; compositions MH, to MH, represent a single solid phase, and in this range these elements, with samarium, form an isomorphous series of hydrides. The MH, hydrides have a fluorite-type structure, and additional hydrogen is distributed in octahedral inter~tices.~" The deuterides of ytterbium and europium (which give maximum composi- tions YbDl.g8 and EuD,.,J are isostructural with hydrides of alkaline-earth metals.278 An earlier claim that the hydride Gd,H, is formed on heating gadolinium in hydrogen is not supported by detailed pressure-temperature- composition data. Two solid phases exist; the first has cubic structure of ideal composition close to GdH,, the second a hexagonal structure of com- position close to GdH,. The system is a counterpart of the plutonium- hydrogen system.279 New borides PrB,, SmB,, GdB,, and YbB, (iso- morphous with CeB,, ThB,, and UB,) have been prepared by heating the oxide M,O, with boron and carbon at 1500-1800", and their lattice constants measured.280 They are less stable than the known borides MB,. The lower oxide of samarium, SmO, has been prepared by distillation from a Sni-Sm,O, mixture a t 1100-1300" in an argon atmosphere and in complete absence of oxygen. An oxide SmOo.,-,, was also obtained, which may imply the presence of univalent samarium. The oxide EuO is prepared under similar conditions by heating a La-Eu,O, mixture.281
Reaction of hydrogen chloride with ceric oxide (in dioxan) precipi- tates orange needles of hexachloroceric acid as the dioxan complex H,CeC16,4C,H802.282 Kinetic study of the reaction between ColI1 and CeIII ions in perchloric acid indicates that a perchlorate complex of CeIII takes part in the rate-determining step CeC10,2i' + CoOH2+ ---9 CeIV + COII."~ In contrast to the ceric sulphate-hydrogen peroxide reaction, which is fast at pH (1.4, ceric perchlorate solutions above pH 0.7 contain part of the CeIV in the form of a colloidal polymer related to the dimer [Ce-O-CeI6+; this gives a coloured complex with hydrogen peroxide which decomposes
Dipyridinium cerium hexachloride is sufficiently stable to be dried in a slowly.284
vacuum at 120". (C,H6N)2,CeCI, + 4Bu"OH + 6NH3+ Ce(OBuU)* + 2C,H,N + 6NH,CI
On use of isopropyl alcohol, the addition compound Ce(0Pr) ,,PrOH crystal- lises. The pure isopropoxide is used as starting material for the preparation, by alcohol interchange, of alkoxides Ce(OR), where R = Me, Et, Prn, Bun, Bui, Yt-pentyl, and Yteopentyl. Only the neopentyl oxide is volatile (sublimes at 260"/0-05 mm.).285 Apart from this case, the alkoxides resemble the.
2 7 7 R. N. R. Mulford and C. E. Holley, J. Phys. Chem., 1955, 59, 1222; C. E. Holley, R. N. R. Mulford, F. H. Ellinger, TV. C. Koehler, and W. H. Zachariasen, ibid. , p. 1226.
2 7 8 W. L. Korst and J . C. Warf, Acta Cryst., 1956, 9, 452. 279 G. E. Sturdy and R. N. R. Mulford, J . Amer. Chem. Soc., 1956, 78, 1083. 280 B. Post, D. Moskowitz, and F. W. Glaser, ibid., p. 1800. 281 H. A. Eick, N. C. Baenziger, and L. Eyring, ibid., p. 5147. 282 S. S. Moosath and M. R. A. Rao, Current Sci., 1956, 25, 14; S. S. Moosath, Pwc.
283 L. H. Sutcliffe and J . R. Weber, Trans. Faraday Soc., 1956, 52, 1225. 284 M. Ardon and G. Stein, J., 1956, 104. 2 8 5 D. C . Bradley, A. K. Chatterjee, and IV. Wardlaw, ibid., p. 2260.
It undergoes the reaction
Indian Acad. Sci., 1956, 43, A , 272.
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ADDISOX A N D GREENWOOD : THE TRANSITION ELEMENTS. 113
zirconium derivatives in molecular complexity, but the thorium derivatives in their lack of volatility. Of the ceric secondary alkoxides Ce(OCHMe*R), only the tetraisopropoxide is volatile (sublimes at 160-170"/0~05 mm.) .286
The Titanium Group.-At -17" titanium tetraiodide is converted by clinitrogen tetroxide into the anhydrous tetranitrate Ti(NO,),. This is unstable, evolving brown fumes at 10" to give the oxynitrate TiO(NO,),. Zirconium tetraiodide reacts ~ i m i l a r l y . ~ ~ 7 The preparation of titanyl amide in liquid ammonia, and some of its reactions, are summarised in the following scheme.288
KSCN KNH, KNHa
350" I 000" TiO(NH& + (Ti0)3N2 __t T i0 + N2
TiO(S0,) + K,[TiO(SCN),] ___) TiO(NH,), + TiO(NHKh
The thermodynamic properties of the lower chlorides of titanium have been studied in detail. The heats of formation of TiCl,(s) and TiCl,(s) are -172.2 & 0.7 and -123.3 kcal,/mole from measurements of heats of solu-
compared with -169.1 & 0.4 and -120-1 & 0.8 kcal./mole deter- mined by direct chlorination.29o The disproportionation of titanium di- chloride has also been r e - e ~ a r n i n e d . ~ ~ ~ ~ 291 The range of molecular addition compounds which tetrachlorides of titanium-group elements form with organic compounds has been extended. Fusion diagrams of titanium tetra- chloride with 15 monocarboxylic esters show 1 : 1 addition compounds, of which the complex TiCl,,Me*CO,Me has the highest melting point ( 145°).292 Dipole moments of complexes with esters and nitriies have been recorded.2s3 Zirconium and hafnium tetrachlorides give with acetonitrile a solid phase MC1,,2MeCN together with two liquid phases of variable composition ; the maximurn separation factor of hafnium and zirconium between the two phases is Hf/Zr = 1 ~ 8 . ~ ~ ~
The readiness with which the alkoxy-derivatives (RO),TiCl, - , are obtained by direct reaction of alkyl orthotitanates with titanium tetra- chloride depends upon the reaction medium. Each of the compounds in which = 1, 2, 3, or 4 forms an addition compound (RO),TiC1,-,,C,HloNH, and in piperidine the addition compounds are sufficiently stable to be used in separation of individual products.295 The solvolysis MCl, 4- nROH += (RO),,MCl,-, + nHCl in methyl or ethyl alcohol is more extensive with hafnium than with zirconium t e t r a c h l ~ r i d e . ~ ~ ~ The chemistry of thorium alkoxides Th(OR), has been extended to include 12-butyl, 92-pentyl, and
2 8 6 D. C. Bradley, A. K. Chatterjee, and W. Wardlaw, J . , 1956, 3469. 2 8 7 V. Gutinann and H. Tannenberger, filonatsh., 1956, 87, 421. 2 8 8 0. Sclimitz-Dumont and F. Fiichtenbusch, 2. al-zorg. Chem., 1956, 284, 278. 289 D. G. Clifton and G. E. MacWood, J . Phys . Chem., 1956, 60, 309, 311; B. S.
2Qo W. F. Krieve, S. P. Vango, and D. M. Mason, J . Chem. Phys., 1056, 25, 519;
291 A3. Farber and A. J. Darnell, ibid. , p. 526. i92 Yu. A. Lysenko, 0. A. Osipov, and Ye. K. Akopov, Zhur. neorg. Khim, 1956,
293 0. A. Osipov, J . Geia. Chem. (U.S.S.R.), 1956, 26, 343. 294 E. &I. Larsen and LaV. E. Trevorrow, J . Inovg. Nucleav Chem., 1966, 2, 254. 295 A. N. Nesmeyanov, R. Kh. Freidlina, and E. M. Brainina, Bull. Acad. Sci.
Sanderson and G. E. MacWood, ibid., pp. 314, 316.
D. Altman, 11. Farber, and D. M. Mason, ibid., p. 531.
1, 536.
U.S.S.R., 1954, 861. C. R. Simmons and R. S. Hansen, J . Phys. Chem., 1955, 59, 1072.
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114 INORGANIC CHEMISTRY.
lzeopen tyl derivatives. In benzene solution they have molecular com- plexities 6-44, 6.20, and 4.01 respectively ; none will volatilise in a vacuum.285 Secondary alkoxides Th(0CHEt-R),, where R = Me or Et, are also non- volatile, and polymeric in benzene.286
A mono- and a tri-hydrate of zirconium tetrafluoride have been identified by X-ray diffraction. The monohydrate is formed at 100" from the tri- hydrate, and hydrolysis to zirconyl fluoride and zirconium oxide occurs a t 250°.297 An X-ray investigation of the thorium-silicon system shows the existence of p-ThSi, (in addition to the known a-ThSi2), ThSi, and Th3Si2. All are unstable in air.298
The Vanadium Group.-Dipyridyl complexes of vanadium in the oxid- ation states +1, 0, and -1 have been isolated. When the salt [V11dipy3]12 is reduced with magnesium or zinc in aqueous alcohol, the neutral complex podipy3] is formed ; it gives blue solutions not having appreciable electrical conductivity.299 Oxidation with one equivalent of iodine gives a red-violet solution containifig the ion [Vrdipy3]-'-, and reduction of a [Vodipy,] solution in tetrahydrofuran (THF) containing a lithium salt gives black crystals of formula Li[V-Idipy3],4THF. Representation of this as a V-1 compound is supported by its diarnagneti~m.~W The valency of vanadium in its ternary nitrides differs from that in the binary nitride VN (as with titanium, which gives TIN, but Li,TiN,). When the compounds Li,N and VN are heated together, nitrogen is evolved leaving a product of approximate composition Li,VN,, the chemical properties of which indicate the presence of vana- dium(v) .301
Spectrophotometric and potentiometric studies in perchlorate media a t 25" indicate that the orange-yellow vanadium(v) species present in acid solution are relatively few. In the pH range 0.5-1.3, the cation VO,+(aq.) is the only species. In the pH range 1-3-66 the isopolyvanadate ions are H,Vlo0284-(aq.), HVlo02,5-(aq.), and Vlo02,6-(aq.), -in proportions which depend on pHO3O2 Niobium pentoxide dissolves (4 g./lOO ml.) in concentrated hydrochloric acid and chloro-complexes are formed. In solutions in which hydrogen- and chloride-ion concentrations were varied, the three species Nb(OH),Cl,-, Nb(OH)Cl,+, and Nb(OH),Cl, were identified.303 The degree of condensation of the isopolytantalate ion has been re-examined. Diffusion coefficients, cryoscopy, and conductivity measurements indicate that in alkaline solution the only ion present is [Ta5016-j7-(aq.), which undergoes no change throughout the alkaline pH range. The ion is formulated from the orthotantalate ion TaO,,-, the four oxygen atoms being replaced by TaO, groups.304
297 R. VCT. M. D'Eye, J. P. Burden, and E. A. Harper, J . Inorg. Nuclear Chem., 1956, 2, 192.
29* E. L. Jacobson, R. D. Freeman, A. G. Tharp. and A. W. Searcy, J . Amer. Chem. Soc., 1956, 78, 4850.
299 S. Herzog, Naturwiss., 1956, 43, 35. 300 S. Herzog and R. Taube, ibid., p. 349. 301 I<. Juza and W. Gieren. ibid., p. 225. ~2 I;. J. C. Rossotti and H. Rossotti, Acta Chem. Scmd. , 1956, 10, 957. 303 J . H. Kanzelmeyer, J. Ryan, and H. Freund, J. Amer. Chem. Soc., 1966, 78,
3020 ; see also D. I. Kurbatov and N. V. Demenev, Zhur. priklad. Khim., 1966,29,944. 30* G. Jander and D. Ertel, J . Inorg. Nuclear Chem., 1956, 3, 139; see also V. I.
Spitsyn and N. N. Shavrova, Zhur. obshchei Khim., 1956, 26, 1268.
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ADDlSOK AND GREENWOOD THE TRANSITION ELEMENTS. 115
'I'hermal and X-ray analysis of t,he system K20-V20, shows clear evidence for the five compounds K,0,4V20,, K20,V205, 16K20,9V205, 2K,0,V205 and 3K20,V2O5, but reveals no evidence for the existence of the previously reported allotropic modifications of vanadium pen t~x ide .~ , The K20-T+0, system shows four compounds K20,5T%05, K20,2Ta205, K,O,Ta,O,, and 3K20,Ta,05. Tantalum pentoxide is dimorphic.306
Niobium trifluoride has now been prepared by the action of an HF-H, mixture on niobium hydride (NbH,.,) at 570". It is dark-blue and can be sublimed in a vacuum.3o7 The oxyfluorides Nb0,F and Ta0,F both have the Re03 structure, with fluorine and oxygen atoms randomly distributed in octahedral positions about the metal atom .m8 Tantalum pentaiodide can be prepared by heating the pentoxide with the stoicheiometric quantity of aluminium iodide for 24 hr. a t 230". A similar reaction with niobium pentoxide probably gives the pentaiodide as initial product, but only the tri-iodide is i s ~ l a b l e . ~ ~ ~
The alkoxides of the vanadium-group elements differ markedly from those of the titanium group. The alkoxides Nb(OR), (R = Et, Pr", Run, or n-pentyl) are yellow liquids, and the methoxide is a white crystalline solid of m. p. 60". The methoxides and ethoxides of tantalum are more volatile than those of niobium, but the reverse becomes the case for the higher ~ t - a l k o ~ i d e s . ~ ~ ~ All these ?z-alkoxides are dimeric in benzene, with sexaco- ordinate niobium and tantalum atoms in the molecule. A number of isomeric butoxides and pentyloxides of niobium have been compared ; 311
there is a general increase in volatility with increased branching of the chain. In contrast to tantalum, which forms stable tertiary alkoxides,312 niobium gives no penta-tert.-alkoxides. I ts greater tendency to give oxy-complexes is shown in the formation of oxide-tert.-butoxides of the type Nb,O(OBut), and NbO(OBut),. The molecular complexity of the tantalum alkoxides Ta(OR), is influenced by the donor properties of the solvent. When R = Me, Et, Prn, or Bun the compounds are dimeric in benzene but monomeric in ~ y r i d i n e . ~ ~ ~
The critical potential for electrodeposition of protactinium from 10-1l~- solutions of the fluoride is -1.20 v in relation to the hydrogen electrode. The normal potential of the Pa-PaF,2- couple is near 1.0 v. Conditions for optimum deposition on nickel, gold, and platinum cathodes, and on a lead dioxide anode, have been defined.,l*
The Chromium Group and Transuranium Elements.-Nitrosyl reineckate, [Cr(NCS),(NCS*NO) (NH3)2], h'as the constitution shown and is not a
305 F. Holtzberg, A. Reisman, M. Berry, and M. Berkenblit, J . Amer. Chem. Soc., 1956, 78, 1536; see also V. V. Illarionov, R. P. Ozerov, and Y . V. Kil'disheva, Zhur. ncorg. Khim., 1956, 1, 775 .
306 A. Reisman, F. Holtzberg, M. Berkenblit, and M. Berry, ibid., p. 4514. 307 P. Ehrlich, F. Ploger, and G. Pietzka, 2. anorg. Chem., 1956, 282, 19. 308 L. K. Frevel and H. W. Rinn, Acta Cryst.. 1956, 9, 626. 309 M. Chaigneau, Compt. relad., 1956, 242, 263. 310 I). C. Bradley, B. N. Chakravarti, and W. Wardlaw, J. , 1956, 2381. 311 Idem, ibid., p. 4439. 312 D. C. Bradley, W. ?Yardlaw, and A. Whitley, ibid. , p. 1139. 313 Idem, ibid., p. 5 . 314 C. Ferradini, J . Chin&. Phys., 1956,53, 714; C. Ferradini and M. Haissinsky, ibid.,
p. 722.
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116 INORGANIC CHEMISTRY.
nitrosonium salt. On being warmed, its soJutions decompose to give binuclear complexes :
- 2NO 2[Cr(NCS),(NCS*N0)(NH8)J ___t [Cr(NH3),(NCS),NCSaSCN(NCS),(NH,),Cr]
- (SCNIo - rCr(NHd2(NCS)31,
The complexes are linked through sulphur atoms.315 The oxidation of chromous perchlorate solutions by molecular oxygen involves primary formation of oxygen-bridged chromic c0mplcxes.~~6
Red magnesium peroxychromate, Mg,(CrO,),, 13H,O, and various double salts of calcium, strontium, and barium peroxychromates with alkali metal peroxychromates, e.g., Ca5K2(Cr,0,,),,19H,0 and Ca2K2(Cr20,,),7H2O have been described.317 The acid H,[Mo,07*0,] has been recognised in concen- trated perchloric acid solutions of molybdenum(v1) containing hydrogen peroxide. '' Perniolybdic acid " is regarded as a salt of this acid with the cation [HM0206]', which itself is not p e r ~ x i d i c . ~ ~ ~
New phosphates of sexavaleiit molybdenum have been prepared by crystallisation from solutions of molybdenum trioxide in glacial phosphoric acid. From mixtures heated at 600", crystals of composition MoO,,P2O5 ( A ) and ZMoO,,P,O, (13) are obtained. From mixtures heated at NO", 2Mo0,,P20,,3H,0 (C) crystallises ; (C) is inolybdenyl hydrogen phosphate (Mo02)HP0,,H20 which at 300" gives the pyrophosphate (MoO,),P,O, (23) ; ( A ) is probably molybdenyl polymetaphosphate ( M O O , ) ~ + ( P O ~ - ) ~ . ~ ~ ~ From a melt of MOO, and Graham's salt (polymeric NaPO,), the compound Na,0,2Mo03,P205, which is probably inolybdenyl sodium orthophosphate (MoO,)NaPO,, crystallises.320 Analogous tungsten compounds are formed. Unusual heteropoly-anions have been described which contain both cobalt and tungsten in the anion :
oxidation H+ [ c o ~ ~ c o ~ I w , z o 4 J s - ____) [co~~co~'Iwl,o,2]'- ----+ [COIII( W20,)J9-
The first two polyanions consist of a CoII ion enclosed in a basket of twelve WO, octahedra ; the other CoT1 ion (which is less readily oxidised but readily removed by acid) is in a COO, octahedron outside the basket but attached by sharing corners with WO,
Ternary oxides of quadrivalent molybdenum of formula hI,Mo,O,, (M = Mg2+, Zn2', Co2+, Fe2+) are formed when appropriate oxide mixtures are heated at 1150".322 Thermogravimetric and X-ray analysis of the many stages involved in the reduction of tungsten ti-ioxide by hydrogen have been described.323 The crystal chemistry of oxygen compounds of molybdenum
315 F. Seel, A. Hauser, and D. Wesemann, 2. afioi'g. Chem., 1956, 283, 351. 316 M. Ardon and G. Stein, J., 1956, 2095. 317 J. Beltran Martinez and M. Roca Adell, Publ. Inst. Quim. Aloizso Barba, 1955,
316 F. Chauveau, P. Souchay, and G. Tridot, Bull. SOC. chim. France, 1955, 1519. 319 I. Schulz, 2. anorg. Chem., 1955, 281, 99. 320 Idem, ibid., 1956, 284, 31. 321 L. C . W. Balier and T. P. McCutcheon, J . Anzer. Chem. SOC., 1966, 78, 4503. 322 R. W. Schmid and C. N. Reilley, ibid., p. 2909. 323 A. J. Hegediis, T. Millner, J. Neugebauer, and K. SasvBri, 2. anorg. Chew., 1955,
9, 1, 15.
281, 64.
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ADI)ISOX AND GREENWOOD : THE TRANSITION ELEMENTS. 117
and tungsten having structural elements of ReO, or perovskite type has been reviewed.324 When water vapour-nitrogen mixtures are passed over tungsten trioxide at lOOO", the solid removed is a linear function of the water vapour pressure ; \VO,(OH), is the volatile species.325
Complex fluorides of general formula M,[MoF,] and M2DVF,] are formed by condensing molybdenum or tungsten hexafluoride on solid alkali metal fluorides (M = K, Rb, Cs). The complexes are decomposed by bromine trifluoride yielding te t raf l~orobromites .~~~ Molybdenum hexafluoride can be handled in normal glass vacuum apparatus if sodium fluoride is used to remove traces of hydrogen The thermodynamic propertes of the system Moo3-HC1 can be accounted for on the assumption that gaseous molybdenum oxychloride, MoO,Cl,, is formed with traces of water present.328 When chlorotungstates [WC1,]G-z are reduced by tin in hydrochloric acid, the equilibrium in solution is represented by 3W,C1,3- + C1- + 2vI',c1145-, and the compounds K,W,Cl, and K,W,Cl,, can be crystallised. The latter, a dark green solid, gives deep-red solutions in water.329 The former, on refluxing with aniline or pyridine, gives the non-electrolytes W,C16,(C,H5*NH,), and W,C16,(C5H5N), which have the same spatial distribution as the parent W,C1,3- ion, i.e., two fused octahedra with a common triangular face of chlorine ~oIIs.~~O Treatment of either potassium salt with bromine vapour at 450" yields dark crystals of the mixed halide W B r C1,.331
The same uranium mixed halide UClF, is obtained by each of the re- actions UO,F,-CCl,, U0,F2-CCl,~CC1:CC12, UF4-UCl,, UF3-Cl,,and UF,-CCl,, and has been shown to be the product to which the formula UCl,F, was previously assigned.332 In perchlorate solution, complex formation takes place between U0,2+ and F- ions, with the ion UO,F4,- as the upper limit.,,, More extensive information is available on the U03-H,0 system. At 180" an orthorhombic hydrate U03,0.8H,0 is stable; between 200" and 280" the phase UO,,l-OH,O appears, and the hemihydrate U0,,0.5H20 is stable above 280".33p Solvent-extraction and spectrophotometric studies show that enhanced extraction of uranyl nitrate into ketonic solvents in the presence of a substituted ammonium nitrate is due to the formation of the ionic complex R+[UO,(NO,),]- (R = alkylammonium, a l k y l p y r i d i n i ~ m ) . ~ ~ ~
An important series of papers describe organic compounds of uranium.sG* Twenty-seven uranium( ~ v ) dicarbonyl chelates
324 A. MagnCli, J . Inorg. Nztclear Chesn., 1956, 2, 330. 325 0. Glemser and H. G. Volz, Natztrwiss., 1956, 43, 33. 326 B. Cox, D. W. -4. Sharp, and A. G. Sharpe, J. , 1956, 1242. 327 T. A. O'Donnell, ibid., p. 4681. 328 N. Hultgren and L. Brewer, J . Phys. Chem., 1956, 60, 947. 329 R. A. Laudise and R. C . Young, J . Amer. Chem. SOC., 1955, 77, 5288. 330 H. B. Jonassen, S. Cantor, and A. R. Tarsey, ibid. , 1956, 78, 271. 331 R. C. Young and R. A. Laudise, ihid. , p. 4861. 332 A. W. Savage, ihid. , p. 2700. 333 S. Ahrland, R. Larsson, and K. Rosengren, Acta Chem. Scand. , 1956, 10, $05. 334 J. K. Dawson, E. Wait, K. Alcock, and D. R. Chilton, J . , 1956, 3531. 336 L. Kaplan, R. A. Hildebrandt, and M. Ader, J . Inorg. Nuclear Chem., 1956,2, 153. 336 H. Gilman, R. G. Jones, E. Bindschadler, D. Blume, G. Karmas, G. A. Martin,
J . F. Nobis, J. R. Thirtle, H. L. Yale, and F. A. Yoeinan, J . Amer. Chem. Soc., 1956, 78, 2790.
337 R. G. Jones, G. Karmas, and G. A. Martin, and H. Gilman, ibid., p. 4285; R. G.
Sodium fluoride does not react.
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118 INORGANIC CHEMISTRY.
U(R*CO*CHCO*R1) , and fourteen uranyl compounds UO,( R*CO*CH*CO*R1), have been prepared. The former are mostly volatile but the latter are not.336 Uranium diethylamide U(NEt,), is a green volatile compound, m. p. 35.5"; attempts to prepare other UIv dialkylamides were unsuccessful. From the diethylamide, reaction with thiols gives Urn ethyl and n-butyl mercaptides U(SR), as light green pyrophoric solids. The methoxide and ethoxide U(OR), are readily decomposed by moisture. A number of uranium(v) alkoxides U(OR), have also been isolated ; the ethoxide U(OEt), is thermally stable and readily distilled.%,
The recent chemistry of the transuranium elements has been reviewed by H. J. Emelkus and A. G . Maddock.338 Plutonium nitrate separates as the pentahydrate Pu(N0,),,5H20 on slow crystallisation from a concentrated solution in nitric acid. The dilute aqueous solution is brown, changing rapidly to green as colloidal plutonium is formed.339 Plutonium nitride, PUN, is prepared from the metal and nitrogen above 230". Unlike uranium nitride, it is completely hydrolysed in moist air in a few hours at 80-90°.340 Examination of the plutonium-hydrogen system shows that in the range PuH,-PuH2.,, hydrogen is in solid solution in the fluorite structure of PuH,. Between PuH,,, and PuH, a hexagonal hydride phase appears.341 Fuller information is now published on the preparation and properties of plutonium hexafluoride. It may be formed in the following ways : (1) 2Pu0, + 12HF + 0, __t 2PuF, + 6H,O; (2) 2PuF, + 0, + PuF, + PuO,F,; (3) PuF, + F, _t PuF, (AmF, is not produced under these conditions) ; (4) 2PuF3 + 3F, + 2PuF, ; and (5) Pu0, + 3F, + PuF, + 0,. The hexafluoride is a white crystalline solid, melting at 50.7" to a brown liquid. Low-temperature hydrolysis with traces of moisture gives the oxyfluoride PuO,F,, but hydrolysis by water a t room temperature is vio- lent, giving PuO, and P u F , . ~ ~ The small magnetic susceptibility of the PuF, molecule has been considered in terms of its two non-bonding electrons.343 Purv in hydrochloric acid forms the complex ion P U C ~ ~ + . ~ Since separation of tervalent plutonium, americium, and curium occurs on ion-exchange columns in chloride solutions, chloride complex-formation has been studied as a function of hydrochloric acid concentration. Dissociation constants of the monochloride complexes MC12+ are identical in dilute acid, but in strong acid the complexing powers (MC1,-) are in the order Pu >Am > Cm. The results are of interest with reference to 5f orbital h y d r i d i s a t i ~ n . ~ ~ ~
Conditions have been given for quantitative deposition of ,,lArn on steel, platinum, or copper electrodes.a6 The 248-isotope of berkelium Jones, E. Bindschadler, G. Karmas, F. A. Yoeman, and H . Gilman, J . Anzer. Chem. SOC., 1956, 78, 4287; R. G. Jones, E. Bindschadler, G. Karmas, G. A. Martin, J. R. Thirtle, F. A. Yoeman, and H. Gilman, ibid., p. 4289.
338 H. J. Emel6us and A. G. Maddock, Osterr. Chem.-Ztg., 1956, 57, 153. 339 J. L. Drummond and G. A. Welch, J., 1956, 2565. 340 F. Brown, H. M. Ockenden, and G. A. Welch, J . , 1955, 4196. 341 R. N. R. Mulford and G. E. Sturdy, J . Amer. Chem. Soc., 1956, 78, 3897. 342 C. J. Mandleberg, H. K. Rae, R. Hurst, G. Long, D. Davies, and K. E. Francis,
J . Inorg. Nuclear Chem., 1956, 2, 358. 368; B. Weinstock and J. G. Malm, ibid., p. 380. 843 D. M. Gruen, J . G. Malm, and B. Weinstock, J . Chem. Phys., 1956, 24, 905. 344 S. W. Rabideau and H. D. Cowan, J . Amer. Chem. SOC., 1955, 71, 6145. 346 M. Ward and G. A. Welch, J . Inorg. Nuclear Chem., 1956, 2, 395. 346 R . KO, Nucleonics, 1956, 14, No. 7, 74.
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ADDISON A N D GREENWOOD : THE TRANSITION ELEMENTS. 119
(half-life 23 & 5 hr.) is formed by 25 Mev-helium-ion bombardment of 24QCm ; the berkelium fraction is separated from curium, californium, and fission products by precipitation and ion e~change.3~7 The half-life of 245Bk is 5 daysu8 Some nuclides were found in the debris from the 1952 thermonuclear test which have not been detected in reactor irradiation products. These include 24eCm and 2aCf (spontaneous fission half-life < 1.2 x lo7 yr., and 55 days).a9 Neutron irradiation of plutonium has yielded isotopes of einsteinium * (253E, 254E, 255E) and fermium * (2aFm, 255Fm).350 The decay of 252Fm has been studied.351
The Manganese Group.-Manganese shows univalency in its isocyanide complexes. Each product of the reaction
2Mn12 + I2RNC [Mn(RNC),]I 4- [Mn(RNC)J2
contains univalent manganese, and is diamagnetic. The monoiodide is con- verted into the tri-iodide by iodine. Complex isocyanides [Mn(RNC),]X have been isolated in which R = MeO*C,H,*NC, Me*C,H,*NC, C,H,-NC, $-C1*C6H4*NC and X = C103-, Cl-, Br-, OH-, PF,-, HCO,-, BF,- and BPh4-.353 The reactivity of the oxyanions MnO,-, Mn0,2-, and MnOd3- has been compared in terms of the free-energy changes involved.353
Values for the electrode potentials between different valency states of technetium have been revised.3a Radioactive technetium almost certainly exists in terrestrial substances in minute quantities (e.g., in uranium ores by spontaneous fission of 238U), but the search for primordial technetium has been unsuccessful: The possibility of discovering primordial technetium depends on whether the 9 8 T ~ half-life exceeds lo8 years, and there is evidence that it is near lo5 years. Technetium is believed not to exist in the sun.355
Rhenium of high purity (> 99.95%) has been prepared by hydrolysis of the pentachloride, and hydrogen reduction of the hydrated rhenium dioxide so formed.356 The yellow solution obtained on reduction of the trichloride Re,Cl, in sodium cyanide solution with sodium amalgam represents quantita- tive reduction to rhenium(1) cyanide. Potentiometric measurements indicate that oxidation of this solution by ferricyanide proceeds in two distinct steps Re1 + Rem and ReITr + ReV.357 Fluororhenic acid H2ReF, cannot be
347 E. K. Hulet, Phys. Rev., 1956, 102, 182. 348 L. B. Magnusson, A. M. Friedman, D. Engelkemeir, P. R. Fields, and F. Wagner,
ibid.. p. 1097. 349 P. R. Fields, M. H. Studier, H. Diamond, J. F. Mech, M. G. Inghram, G. L. Pyle,
C. M. Stevens, S. Fried, W. M. Manning, A. Ghiorso, S. G. Thompson, G. H. Higgins, and G. T. Seaborg, ibid., p. 180.
260 M. Jones, R. P. Schuman, J. P. Butler, G. Cowper, T. A. Eastwood, and H. G. Jackson, ibid.. p. 203.
351 A. M. Friedman, J. E. Gindler, R. F. Barnes, R. Sjoblom, and P. R. Fields, ibid., p. 585.
352 A. Sacco and L. Naldini, Gazzelta, 1956, 86, 20'7. 353 A. Camngton and M. C. R. Symons, J., 1956, 3373. 354 G. H. Cartledge and W. T. Smith, J . Phys. Chem., 1955, 59, 1111. 3 5 5 F. Daniels, ibid., 1956, 60, 705. 356 D. M. Rosenbaum, R. J. Runck, and I. E. Campbell, J . Electrochem. Soc.. 1966.
5 5 7 J. Meier and W. D. Treadwell, Helv. Chim. Acta, 19.55, 38, 1679.
* The names einsteinium and fermium (E and Fm) for elements of atomic number 99 and 100 respectively have been used in the literature, but have not yet received approval from I.U.P.A.C.
103, 618.
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120 INORGANIC CHEMISTRY.
isolated as a solid by evaporation of its solutions since this results in decomposi- tion to rhenium dioxide. However, many salts "a+, K+, Rb+, Cs+, NH4+, Ba2+, Ni(NH,),2+, CO(NH3)63+] containing the ReF,2- ion are now character- ised. Both the acid and its salts shows a surprising stability towards alkalies and strong
The Iron Group.-A quadrivalent iron compound is produced by nitric acid oxidation of the complex [FeCl,(diarsine),J [FeCl,] (where diarsine = o- phenylenebisdimethylarsine). I t has the formula [FerVC12(diarsine)J [FeCl,], and a magnetic moment indicating two unpaired electrons as required for FeIV with six d2sp3 bonds. In titration with iodide ions, one equi- valent of iodine is liberated.359 Iron pentacarbonyl is decomposed by nitro- gen sulphide, N,S,, in benzene solution to give a black solid Fe(NS),, and the magnetic moment again indicates two unpaired electrons.360 The pre- paration of a range of ferrates(vI), orthoferrates(Iv), and metaferrates(1v) of alkali and alkaline-earth metals has been described.361 A new deca- hydrate FeCl,, 10H20, melting incongruently a t O", has been recognised during phase study of the FeC1,-H20 system.362
A series of nitratoaquo-nitrosylruthenium complexes, of general formula [RuNO(NO,),(OH), -g(H20)2] have been identified which further illustrate the pronounced stability of the RuN03+ complex. In aqueous solution they give rise to both anionic and cationic ruthenium species. The trinitrato- complex [RuN0(NO3),(H2O),] is formed by the action of boiling 8x-nitric acid on nitrosylruthenium and its proton dissociation and hydrolysis has been examined.364 Hydrogen peroxide reduces ruthenium tetroxide in nitric acid to give a deep red solution containing a series of hydroxyaquo-complexes of general formula [Ru(OH),(H,O), -J(NO,), --2.
No evidence was found for the parent compound [RU(H20)6](N03)4,365 Potassium fluororuthenate(II1) K,RuF, is prepared by fusing an hydrous potassium hydrogen fluoride at 250" with ruthenium tri-iodide. Unless oxygen is rigidly excluded, K,RuF, is formed also.366
Some unusual ethylenediamine complexes of osmium ( ~ v ) have been described. Ammonium hexabromo-osmate( ~ v ) , (NH,),[OsBr,], reacts exo- thermally with anhydrous ethylenediamine giving the pink sexacovalent 0sIv complex [Os en (en-H),I2+ (BI--)~ [(en-H) represents a molecule of ethylenedi- amine less one proton]. This is readily reduced to [Os en,(en-H)]3+(Br-)3, maintaining the 0sIv valency state, and an additional molecule of ethylenediamine can be added to yield the %covalent OsIV complex [Os en2(en-H)2]Br2.365 From the Raman and infrared spectrum of liquid
3 6 8 R. D. Peacock, J . , 1956, 1291; E. Weise, 2. anorg. Chem., 1956, 283, 377. 359 R. S. Nyholm and R. V. Parish, Chem. and Ind., 1956, 470. 360 M. Goehring and K.-W. Daum, 2. anorg. Chem., 1956, 282, 83. 361 W. F. Linke, J. Phys. Chem., 1956, 60, 91. 362 R. Scholder, F. Kindervater, and W. Zeiss, 2. anorg. Chem., 1056, 283, 338;
363 J. M. Fletcher, I. L. Jenkins, F. M. Lever, F. S. Martin, A. R. Powell, and R.
364 I. L. Jenkins and A. G. Wain, ibid., 1956, 3, 28. s65 J. S. Anderson and J . D. M. McConnell, ibid., 1955, 1, 371. 366 R. D. Peacock, Chem. and Ind., 1956, 1391. 367 F. P. Dwyer and J. W. Hogarth, J . Amer. Chem. SOC., 1965, 77, 6152.
R. Scholder, H. von Bunsen, F. Kindervater, and W. Zeiss, ibid., 1956, 282, 268.
Todd, J . Inorg. Nuclear Chem., 1955, 1, 378.
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ADDISON AND GREENWOOD : THE TRANSITION ELEMENTS. 121
osmium tetroxide it is deduced that the molecule is regular tetrahedral. Since the Raman spectra of the Re0,- and WO,,- ions are closely similar, it is concluded that these ions are also tetrahedral, and not octahedral owing to co-ordination of water molecules as previously supposed.368
The Cobalt Group.-X-Ray analysis of bis-(NN-dimethy1dithiocarbamato)- nitrosylcobalt(II), [Co(S,CNMeJ,(NO)], has shown this molecule to be an example of square pyramidal configuration in a quinqueco-ordinate complex. The cobalt atom lies 0-5 A above the plane of the four sulphur atoms (24); in this structure the lines join bonded atoms
The NO group is inclined at an angle of 135" tothe vertical axis of the pyramid, and its bonding is therefore unusual. It may well Me2N/c\s/ \s /iiNMez be a r-complex in which the N and 0 atoms are arranged unsymmetrically because of the difference in their electronegativit ie~.~~~ The quadrico-ordinate complex [CO~~CI,, (CH3*c6H4*NH2),] has been shown crystallographically to be planar,370 and the infrared spectrum of the complex HIColIIC1,, (dimethylglyoxime),], when normal and deuterated dimethylglyoxime are used, justifies the assump- tion that -0-H-O-bonds are present in the dimethylglyoxime plane.371 Outer-sphere association of the cobaltammine ions [CO(NH,),]~+ and [CO(NH,),,H,O]~+ with sulphate ions in solution, which is responsible for immediate changes in the absorption spectrum, has been studied quanti- tatively and equilibrium constants evaluated.372 The compounds Co30, and ZnCo,O, have spinel structures, and the very low paramagnetic suscepti- bility indicates that Co3+ ions are situated in octahedral interstices and covalently bonded as in other CoIII c0mplexes.~7~
The interaction of bromine trifluoride and sodium hexachlororhodate(II1) has been rein~estigated.~,~ The product, identified from its predicted X-ray powder pattern, is the complex Na,RhF6, and not Na3RhF, as originally thought. Some sexico-ordinate sulphitoammine complexes of rhodium and iridium have been described in which the SO3,- ion acts as a mono- or a bi-dentate ligand.374
The chemistry of iridium fluorides has been re-examined and extended. Iridium hexafluoride (m. p. 44", b. p. 53") gives a deep yellow vapour stable to red heat. Its magnetic moment (3.3 B.M.) is consistent with octahedral configuration. When kept in glass rigorously dried, there is no evidence of the oxyfluoride IrOF,, thought to be formed by reaction with glass. In its reactions, reduction to IrV frequently occurs ; thus sulphur tetrafluoride and sulphur dioxide give IrF,,SF, (which may have the ionic form SF3+JrF,-) and IrF,,SO,. Nitric oxide and gaseous dinitrogen tetroxide give the
without indicating the bond multiplicity. NO I
/ s -cO - s\
ass L. A. Woodward and H. L. Roberts, Trans. Faraday SOC., 1956, 52, 615. 368 P. R. H. Alderman and P. G. Owston, Nature, 1956, 178, 1071. 370 G. B. Bokii, T. I. Malinovskii, and A. V. Ablov, Kristallografiya, 1956, 1, 49. 371 A. Nakahara, J . Fujita, and R. Tsuchida, Bull. Chem. SOC. Japan, 1956, 29, 296.
s73 P. Cossee, Rec. Tvav. chim., 1956, 75, 1089. 874 V. V. Lebedinskii and 2. M. Novozhenyuk, Izvest. Sekt. PZuatiny, 1955, No. 29,
F. A. Posey and H. Taube, J . Amev. Chem. SOC., 1956, 78, 15.
66; V. V. Lebedinslrii and Ye. V. Shenderetskaya, ibid., 1955, No. 30, 99.
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122 INOHGANIC CHEMISTRY.
nitrosonium and nitronium compounds (NO),IrF, and (NO,),IrF, ; each loses an atom of fluorine on being heated. As with osmium, no simple pentafluoride of iridium has been found. Above ZOO", iridium hexafluoride attacks glass to give the tetrafluoride (m. p. 1 0 6 O ) , which is reduced to the trifluoride by heating in an atmosphere of sulphur tetrafl~oride.,'~
The Nickel Group.-In solutions 2-3 molar in alkali-metal chlorate or chloride, electrolytic reduction of Nirl to NiI is the principal process.376 The small magnetic moment of the complex fluoride KNiF, has been shown to be due to antiferromagnetism; complexes of the type KMIIF, (M = Mn, Fe, Co, Ni, Cu, Zn) all have perovskite structures and are an t i fe r r~magnet ic .~~~ Magnetic properties of the complexes Ni(PEt,),X, are consistent with the square planar structure when X = C1-, Br-, or I-, and the tetrahedral structure when X = X-Ray investigation of bisacetylacetone- nickel(r1) shows it to be the trinuclear Ni3(C,H,0,)G with nickel atoms almost c01linea.r.~~~ The infrared spectrum of the [Ni,(cN),l4- ion shows absorption in the C=N region only. Bridging does not therefore occur by C=N groups, and the nature of this bridging is not so well understood as was thought. It may involve bridging C-N groups using three-centre molecular orbitals.380 Exchange of [14C]ethylenediamine with the [Ni enJ2+ ion occurs at a measur- able rate, whereas exchange with [Zn en,]", [Cu en2I2+, and [Hg en,]2t is immeasurably fast .381
The complexes [Pd(diarsine),X,] formed by Pdl[ salts with o-phenylene- bisdimethylarsine present an interesting range of co-ordination numbers. The colourless diperchlorate is the 4-co-ordinated [Pd(diarsine),] (C104),. When X = C1, Br, I, CNS, and NO, highly coloured compounds are obtained which behave as uni-univalent electrolytes in nitrobenzene, and are 5-co- ordinated complexes of the type [Pd(diarsine),X]X. In the solid state, [Pd(diarsine),I,] has a distorted octahedral structure.382 Methods used to prepare isocyanonickel, Ni(RNC),, give diisocyanopalladiuin(0) compounds Pd(RNC), (R = phenyl, 9-tolyl, 9-anisyl) which are not analogous and are probably polymeric.383 Bridged complexes of palladium containing thiol (e.g., alkylthiobenzoic acid) bridge groups are less reactive (i.e., the bridging is stronger) than halogen-bridged complexes.384 Successive equilibrium constants for replacement of rt-octylamine in the complex [PdC1,,(C8H,,NH,)J by tributylphosphine, by use of trimethylpentane as solvent, have been evaluated. The system is characteristic of those found useful for studying equilibrium in water-insoluble complexes.385 The hydroxide Pd(OH), obtained by hydrolysis of sodium palladate(I1) differs from the product
375 P. L. Robinson and G. J. Westland, J., 1956, 4481. 376 R. H. Sanborn and E. F. Orlemann, J. Amer. Chem. Soc., 1956, 78, 4852. 377 R. L. Martin, R. S. Nyholm, and N. C. Stephenson, Chem. and Ind., 1956, 83;
378 R. W. Asmussen, A. Jensen, and H. Soling, Acfa Chern. Sca?zd., 1955, 9, 1391. 379 G. J. Bullen, Nature, 1956, 177, 537. 380 M. F. A. ElSayed and R. K. Sheline, J . Amer. Chenz. SOC., 1956, 78, 702. 381 D. S. Popplewell and R. G. Wilkins, J . , 1955, 4098. 382 C. M. Harris and R. S. Nyholm, J., 1956, 4375. 383 L. Malatesta, Rec. Trav. chim., 1966, 75, 644. 384 S. E. Livingstone, J. , 1956, 1989. 3 8 5 €3. Rileddings and A . R . Bnrkin, ibid., p . 1116.
see also R. W. Asmussen and H. Soling, 2. anorg. Chem., 1956, 283, 3.
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A1)L)ISON AND GREENW001) : THE TRANSITION ELEMENTS. 123
PdO,H,O resulting from the action of heat on acid palladium nitrate solution. The latter contains molecules of water within the Pd-0 lattice.366
Palladium and platinum form tetrathionitrosyl compounds analogous to those of iron, cobalt, and nickel. Palladium dichloride reacts with nitrogen sulphide (N4S4) in methyl alcohol to give red-brown crystals of Pd(NS),, m. p. 165". The platinum compound Pt(NS), (m. p. 144") is formed from chloroplatinic acid and nitrogen sulphide in hot dimethyl- formamide. Both are soluble in organic solvents but insoluble in water.387 An X-ray examination of sesquiethylenediaminetrimethylplatinic iodide, Pt(CH3),J,1*5en, shows that the molecule is a dimer, the two mononuclear complexes being linked through a single ethylenediamine molecule, i.e., [(CH,), en Pt-en-Pt en (CH,),]2f.388 The equilibrium between cis- and trans-forms of (MR,),PtX, (where M = P, As, Sb, and X =halogen) in benzene solution has been studied. The equilibrium shifts towards the tram-form when chlorine is replaced by iodine, and as the homologous series is ascended from R = Me to Prn.389 A detailed infrared spectroscopic investigation of absorption due to N-H stretching modes of vibration has been made, with particular reference to amine complexes of platinous ~hloride.~w Development of the use of infrared spectra to determine whether thiocyanato-groups are in bridge or terminal positions in complexes has made it possible to re-examine the two known isomers of the compound (PPr,n),Pt,C1,(SCN),. Both isomers are now found to have SCN groups in bridging positions, so that geometric isomerism is involved, with -CN groups cis or trans to each other about the planar PtS,Pt ring.391 The course of the thermal dissociation of platinic chloride and bromide has been described.392
The Copper Group.-The remarkably small distance between the two copper atoms (2.64 A) in binuclear cupric acetate Cu,(CH,*C0,),,2H20 has stimulated further work on the metal-metal bonding involved. The temper- ature variation of magnetic susceptibility of this and the anhydrous salt has been measured, and it is suggested that Cu-Cu bonding occurs by lateral overlap of 3dz~-yt orbitals.393 A detailed study has been made of anti- ferromagnetic resonance in hydrated cupric chloride C U C ~ , , ~ H , O . ~ ~ ~ The in- frared spectrum of the ethylenediaminetetra-acetato- (edta) and diaspartato- (asp) copper complexes K,[Cu edta] and K,[Cu(asp),] indicates that all nitrogen atoms and carboxyl groups are co-ordinated to the metal, which is thus sexaco-ordinate. This is consistent with the optical activity of the former.395 For comparison with CuCr204, the ternary chalcogenides CuV,S,, CuCr,S,, CuCr,Se,, and CuCr,Te,, have been prepared by heating
3*6 0. Glemser and G. Peuschel, 2. anorg. Chem., 1955, 281, 44. s87 E. Fluck, M. Goehring, and J. Weiss, ibid., 1956, 287, 51. 388 M. R. Truter and E. G. Cox, J., 1956, 948. 389 J. Chatt and R. G. Wilkins, ibid., p. 525. 3g0 J. Chatt, 1;. A.. Duncanson, and L. M. Venanzi, ibid., p. 2712. 391 J. Chatt and L. A. Duncanson, Nature, 1956, 178, 997. 39* S. A. Shchukarev, T. A. Tolmacheva, M. A. Oranskaya, and L. V. Komandrov-
skaya, Zhwv. neorg. Khim. , 1956, 1, 8 ; S. A. Shchukarev, M. A. Oranskaya, and T. S. Shemyakina, ibid., p. 17.
398 B. N. Figgis and R. L. Martin, I., 1956, 3837. sg4 H. J. Gerritsen,.M. Garber, and G. W. J. Drewes, Physica, 1966, 22, 213, and
refs. therein. 395 S. Kirschner, , J . Anzer. Cheau. SOC., 1956, 78, 2372.
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124 INORGANIC CHEMISTRY.
the binary chalcogenides in equivalent quantities a t 600-800". All crystal- lise in a normal spinel lattice.396
Like the fluoroborate, silver hexafluoro-phosphate, -arsenate, -antimon- ate, -niobate, and -tantalate are soluble in benzene, toluene, and m-xylene. Evaporation of the solution gives addition complexes with the aromatic hydrocarbons (e.g., AgPF,,C,H,). Copper displaces silver from the above silver salts in toluene, forming corresponding cuprous cornpo~nds.~97 Equi- librium constants for complex formation between the aqueous Ag+ ion and cyclic olefins indicate that the reactivity of the olefin as an electron donor in x-complex formation is a function of ring strain ; the constants are in the order cydopentene > cycloheptene > cyc lohe~ene .~~~ The silver perchlorate- dioxan compound AgC1O4,3C,H,O2 has an interesting structure. Silver atoms at the corners of a cube are surrounded by an octahedron of dioxan oxygen atoms, and the dioxan molecules rotate without hindrance.399 Sulphimide silver hydrate AgNS02,H,0 exists as a trimer, and X-ray analysis has revealed that the basic unit in the structure is a &membered ring of alternate N and S atoms.400
In strongly alkaline solution, silver and argentocyanide ions react to give hydroxy-anions [Ag(OH) (CN)]-.401 The ion Ag(IO,),- has been recognised in solution by measurement of the solubility of silver iodate in lithium iodate solutions, by use of radioassay techniq~es.~O~ Solubility and potentiometric methods give evidence for the complex ions Ag132-, Ag143-, and the polynuclear species
However, complex-formation with o-phenylenebisdimethylarsine gives [Au(diarsine),]I, with tetrahedral configuration. Tervalent gold gives the quadricovalent complex [Au(diarsine),13+, but in the presence of halide ions the 5- and 6- covalent complexes [Au(diarsine),XI2+ and [Au(diarsine),X,] + have been identified.404 The acid HAu(CN), has been prepared as colourless crystals by passage of a solution of its potassium salt through the €€+-form of Dowex- 50 resin, followed by rapid evaporation. It loses hydrocyanic acid rapidly at 1200.405 X-Ray analysis of gold(1) iodide indicates that the solid consists of endless zig-zag Au-I-Au-I chains.406
The Zinc Group.-Potentiometric titration of the iodides of zinc, cadmium, and mercury with potassium in liquid ammonia showed only reduction to the metal, and no evidence for the +I oxidation state under these condi- tions.407 The melting-point of anhydrous zinc chloride, for which widely varying values have been reported, is 318"; the anhydrous compound was
and Ag3185-.403 The co-ordination number 4 for univalent gold is unusual.
396 H. Hahn, C . de Lorent, and B. Harder, 2. anorg. Chern., 1956, 283, 138. 397 D. W. A. Sharp and A. G. Sharpe, J.. 1956, 1855, 1858. 398 J . G. Traynham and M. F. Sehnert, J . Amer. Chenz. SOC., 1956, 78, 4024. 388 R. J. Prosen and K. N. Trueblood, Acta Cryst., 1956, 9, 741. 400 K. Fischer and K. R. Andress, 2. anorg. Chem., 1955, 281, 169. 4 0 1 I. M. Kolthoff and J . T. Stock, J . Amer. Chem. SOC., 1956, 78, 2081. 402 J. J. Renier and D. S. Martin, zbid., p. 1833. 403 I. Leden, Acta Chenz. Scand., 1956, 10, 540, 812. 404 C. M. Harris, R. S. Nyholm, and N. A. Stephenson, Rec. Trav. chirn., 1956, 75,
405 R. A. Penneman, E. Staritzky, and L. H. Jones, J . Amer. Chem. Soc., 1956,78, 62. 408 A. Weiss and A. Weiss, 2. Naturforsch., 1956, llb, 604. 407 G. Mr. W a t t and P. S. Gentile, J , Amer. Chem. SOC., 1965, 77, 6462.
687.
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ADDISON AND GREENWOOD : THE TRANSITION ELEMENTS. 125
obtained from zinc and hydrogen chloride, and by dehydration of the hydrated salt in a stream of hydrogen chl0ride.~08 The terpyridyl complex [(terpy)ZnCl,] shows an interesting case of quinquecovalency. The lattice is molecular, the Zn atom being linked in a distorted trigonal bipyramid to three N and two C1 atoms. The cadmium and copper compounds have the same ~ t ruc tu re .~0~ Exchange of 36Cl between zinc, cadmium, and mercury chlorides and liquid nitrosyl chloride is rapid between absorbed nitrosyl chloride and the metal halides, followed by a slow heterogeneous exchange with excess of liquid. This favours the existence of unstable nitrosonium salts of the metal chloride complexes. No exchange occurs between nitrosyl chloride and a stable nitrosonium salt (e.g., (NO),SnC16) or sodium or potas- sium chlorides.410
Cadmium dialkyls CdR, (R = Me, Et, Pri) in liquid propane at < -120" react with hydrogen sulphide giving pure cadmium hydrogen sulphide Cd(HS),. Above -40" this decomposes, evolving hydrogen ~ulphide.~l l Pure anhydrous cadmium chloride can be prepared by the action of chlorine gas on the molten metal, and sublimation of the Formation constants for the complexes CdI+, CdI,, CdI,-, and CdI,2- have been evaluated.413
Crystallographic studies on mercurous salts give further information on H g H g bond lengths. In Hg2(N0,),,2H,0 the H g H g distance is 2.54 0.01 A, and the close approach of a water molecule to each Hg atom [d(Hg-0) = 2.15 A] suggests the presence of an oxonium ion (H2O*Hg*Hg*OH.J2+. The Hg-Hg distance in mercuroiis fluoride is 2.43 -J= 0.04 A, which falls in line with known values 2.53, 2-58, and 2.69 A for the chloride, bromide, and iodide.414 Heptasulphur imide (S,NH) reacts with mercurous nitrate giving the yellow product S,N-Hg*Hg*NS,, which darkens in air and light. Tetrasulphur tetraimide (N4S4H,) yields [HgI(NS)]z.415 The compound described in the literature as mercury amidofluoride, HgNH,F has been shown to have the constitution (Hg,N)F,NH,F ; when Millon's base is treated with aqueous ammonium hydrogen difluoride, the compound separ- ates during 24 hr. as a yellow powder.416 A similar compound Hg,NHBr, has a layer lattice of [Hg,(NH),] units; Br- ions are in holes in the layers and HgBr3- groups between the layers.417 Molecules of a compound HgK, have been identified in the vapour of molten potassium amalgam.418
C. C . ADDISON. N. N. GREENWOOD.
408 D. A. Craw and J. L. Rogers, J., 1956, 217. 409 D. E. C. Corbridge and E. G. Cox, ibid., p. 594. 410 J. Lewis and D. B. Sowerby, ibid., p. 150. 4 l 1 U. Hauschild and 0. GIemser, Naturwiss., 1955, 42, 624. d l 3 J. L. Barton, H. Bloom, and N. E. Richards, Chew. and Ind., 1956, 439. 413 M. Quintin and S. Pelletier, Compt. rend., 1956, 242, 768. 414 D. GrdeniC, J. , 1956, 1312; D. Grdenib and C. DjordejeviC, ibid., p. 1316. 415 M. Goehring and G. Zirker, 2. anorg. Chem., 1956, 285, 70. 416 K. Brodersen and W. Rudorff, ibid., 1956, 287, 24. 417 K. Brodersen, Acta Cryst., 1955, 8, 723. 4 l 8 A. Roeder and W. Morawietz, 2. Elektrochem., 1956, 60, 431.
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