Po/yWron Vol. 12, No. 9, PP. 1047-1053, 1993

Printed in Great Britain

0277~5387193 $6.00+.00 0 1993 Pergamon Press Ltd

REACTIVITY OF PzNz AND P2N2H4 TOWARDS C,&M(CO), (M = Cr, MO). X-RAY STRUCTURE OF I;AC-(CO),Mo[PN,P(O)]

WAI-KWOK WONG”

Department of Chemistry, Hong Kong Baptist College, Kowloon, Hong Kong

and

JINGXING GAO

Department of Chemistry, Xiamen University, Xiamen 361005, Fujian, P.R.C.

WING-TAK WONG*

Department of Chemistry, The University of Hong Kong, Pokfulam Road, Hong Kong

(Received 10 November 1992 ; accepted 18 December 1992)

Abstract-The interaction Of C7HgM(CO)4 (M = Cr, MO) with half an equivalent of P2N2 (P2N2 = N,N’-bis[o-(diphenylphosphino)benzylidene]ethylenedia~ne) in THF at ambient temperature gives [cis-(CO),M]2(P2N2) (I, M = Cr; II, M = MO) in high yield. The inter- action of C7H8M(C0), with 1 equivalent of P2N2 in refluxed THF gives [cis- (CO),M]2(P2N2), ~~c-(CO)~M(PN,P) (III, M = Cr ; IV, M = MO) and ~uc-(CO)~M [PN,P(O)] (V, M = MO). The yield of the products depends on the length of the reaction time. For a short reaction time the major product is [cis-(CO)4M]2(P2N2), whereas for a long reaction time ~uc-(CO)~M(PN~P) is the major product. However, the interaction of

C,HsCr(CO)d with 1 equivalent of P2N2H4 (P2N2H4 = N,N’-bis[o-(diphenyIphos- phino)benzyl]ethylenediamine) in refluxed THF produces [cis-(CO),Cr]2(P2N2H4) (VI) as the only isolated product in high yield. Prolonged refluxing of [cis-(CO),M],(P2N2) with P2N2 in THF does not give &zc-(CO)~M(PN~P). In solution IV slowly oxidizes to V, whose structure has been determined by X-ray crystallography.

The potential of polydentate ligands having both soft and hard base donor atoms as good bridging ligands for the preparation of heterobimetallic com- plexes containing an oxophilic metal and a late tran- sition metal has led to extensive studies on the syn- thesis and reactivities of polydentate ligands containing both phosphine and nitrogen donor groups. l-3 N-N’-bis[o-(diphenylphosphino)benzyl- idenelethylenediamine (P2N2), a tetradentate ligand containing both imino and phosphino groups, has been synthesized for some time ; however,

*Authors to whom correspondence should be addressed.

its reactivity towards transition metals has only been briefly explored.4 We are interested in examining whether transition metals of low oxi- dation state will preferentially interact with the phosphino groups of the P2N2 ligand, leaving the imino groups uncoordinated. Recently, we have briefly described the interaction of P2N2 with C7H8Cr(C0)4, which gave the centrosymmetric dimeric species [cis-(CO)4Cr]2(P2N2) in high yield.5 In this paper we report the detailed study of the reactivity of P2N2 towards C7HgM(CO)4 (M = Cr, MO) and the X-ray diffraction analysis of the com- plex ~~c-(CO)~MO[~N~P(O)].

1047

1048 WAI-KWOK

RESULTS AND DISCUSSION

Preparation of [cis-(CO)4M]2(P2N2) (M = Cr, MO)

(1) M = Cr (I). When C7HsCr(C0)4 was treated with half an equivalent of PINZ in THF at ambient temperature for 16 h dark ‘orange crystals of stoi- chiometry [(CO),Cr],(P2N2) (I) were isolated in high yield (90%). The IR spectrum (KBr) of I ex- hibits three absorptions at 1~996m, 1876~s and 1832s cm- ‘. The absorption patmrn is indicative of a cis configuration for the four terminal carbonyl groups of the two Cr(CO), moieties. The 3’P(1H) NMR spectrum of I exhibits only a singlet at 650.3 ppm. This suggests that the twa phosphorus centres of the P2N2 ligand were coo inated and equivalent. The ‘H NMR spectrum of 1” exhibits a broad singlet, a broad multiplet and a singlet of relative intensity l/14/2 at a&26,7.45 and 4.a4 ppm, respectively. The spectroscopic data suggest’1 that the dimeric species should be symmetrical and Ithat an imino group and a phosphino group of the1 P,N2 ligand should be coordinated to each individual Cr(CO), moiety. This is confirmed by an $-ray diffraction study’ which shows that the P2N2 ligand acts as a bidentate ligand with an imino group and a phosphino group coordinated to each of the two Cr(CO), moieties, which adopt a cis configuration for the four ter- minal carbonyl groups, and the dimeric species has a centro-symmetrical structure (A).

A

(2) M = MO (II). Similar to chromium orange crystals of stoichiometry [(CO),Mo],(P,N,) (II) were isolated in high ykld (900/,) when C7H, Mo(CO), was treated with half an equivalent of PzN2 in THF at ambient temperature for 16 h. The IR spectrum (KBr) of II exhibits three absorptions at 2000m, 1878~s and 183gs cm-r. The absorption pattern is indicative of a bs configuration for the four terminal carbonyl gr ups of the two Mo(CO), moieties. The 3 ‘P{ ‘H} N

+n R spectrum of II exhibits

only a singlet at 632.5 pp . This suggests that the two phosphorus centres of the P2N2 ligand were coordinated and equivalent. The ‘H NMR spec- trum of II exhibits a broad/singlet, a broad multiplet and a singlet of relative intensities l/14/2 at 68.15, 7.49 and 4.13 ppm, respectively. The spectroscopic data of II are very similr to I. This suggest that the structure of II id similar to that of I and thus, structure A is assigned to II.

WONG et al.

Compound II can also be prepared in good yield (72%) by the interaction of (CO)3Mo(CH3CN)s with 1 equivalent of P2N2 in THF at ambient tem- perature for 4-5 h.

Interaction of C7HsM(C0)4 with 1 equivalent of

P,Nz

(1) M = Cr. When C7H8Cr(C0)4 was treated with 1 equivalent of P2N2 in refluxing THF I and dark red crystals of stoichiometry [(CO) ,Cr](PN zP) (III) were isolated. The yields of I and III depended on the length of the reaction time. When refluxed for 4 h I and III were isolated in 86 and 5% yields, respectively. However, when the reaction was refluxed for 16 h I and III were isolated in 12 and 76% yields, respectively. The 31P(1H} NMR spec- trum of III exhibits two singlets of relative inten- sities l/l at 649.5 and - 17.0ppm, respectively. The resonance at 649.5 ppm corresponds to a coor- dinated phosphorus and the resonance at 6- 17.0 ppm corresponds to an uncoordinated phosphorus. This suggests that the P2N2 ligand acts as a tri- dentate ligand with one of its phosphino groups remaining uncoordinated. This is further supported by the ‘H NMR spectrum which exhibits a broad singlet at 69.3 ppm, which corresponds to the pro- ton of the uncoordinated benzylidene, and a broad multiplet at 68.4 ppm, which corresponds to the proton of the coordinated benzylidene. There are two possible structures for III. These are the fat and mer isomers as shown below.

Pry-N-P ‘M’

oc’l’co

N PC co \I 3

O&N-P CO co

fuc mer

B C

The IR spectrum (KBr) of III exhibits two absorptions at 1900s and 1780~s cm- ‘, which is indicative of a fuc configuration for the three ter- minal carbonyl groups.6 Thus, structure B, the fat isomer, is assigned to III.

(2) M = MO. Similar to chromium II and dark red crystals of stoichiometry [(CO),Mo](PN,P) (IV) and [(CO),Mo]pN,P(O)] (V) were isolated when C,H8Mo(C0)4 was treated with 1 equivalent of P,N, in refluxing THF. The yields of II, IV and V depended on the length of the reaction time. When refluxed for 4 h II and IV were the products isolated in 85 and 5% yields, respectively. However, when the reaction was refluxed for 24 h II, IV and V were isolated in 13, 45 and 15% yields, respec- tively. The 31P{ ‘H) NMR spectrum of IV exhibits

two singlets of relative intensities l/l at 634.1 and - 17.4 ppm, respectively. The resonance at 634.1 ppm corresponds to a coordinated phosphorus and the resonance at 6 - 17.4 ppm corresponds to an uncoordinated phosphorus. This suggests that the P2N2 ligand acts as a tridentate ligand with one of its phosphino groups remaining uncoordinated. This is further supported by the ‘H NMR spectrum which exhibits a broad singlet at 69.5 ppm, which corresponds to the proton of the uncoordinated benzylidene, and a broad multiplet at 68.5 ppm which corresponds to the proton of the coordinated benzylidene. The IR spectrum (KBr) of IV exhibits two absorptions at 1902s and 1778~s cm-‘, which is indicative of a fat configuration for the three terminal carbonyl groups. Thus, structure B is assigned to IV as well.

Reactivity of P,N2 and P,N2H, towards C7H,M(C0)4 1049

hexane. The structure consists of two independent but structurally very similar molecules of V and a partially occupying molecule of dichloromethane, all separated by normal van der Waals distances. There are only small c,onformational differences between the two chelated ring systems. A per- spective drawing of V is shown in Fig. 1. Selected bond lengths and angles are listed in Table 1. The structure can be described as a distorted octahedral with the three carbonyl groups in a fuc con- figuration and the uncoordinated phosphine oxi- dized to the corresponding phosphine oxide.

In solution IV was slowly oxidized to V when exposed to air. The oxidation process is con- veniently monitored by 3 ‘P( ‘H} NMR spectro- scopy. 31P{ ‘H} NMR study shows that IV, when dissolved in an undeaerated solution of CDC13, decomposed completely within 6 h to give a com- plex mixture from which the oxidized product V was observed in 30% yield. Unlike IV the chro- mium analogue (III) did not undergo oxidation as readily as IV. In a similar study III was found to be unchanged after leaving it in an undeaerated solution of CDC13 for 48 h.

The IR spectrum (KBr) of V exhibits two absorp- tions at 1902s and 1778~s cm- I, which is indicative of a fuc configuration for the three terminal car- bony1 groups. The 31P{ ‘H) NMR spectrum exhibits two singlets of relative intensities l/l at 633.3 and 31.9 ppm, respectively. The chemical shift of the resonance at 633.3 ppm corresponds to that of coor- dinated phosphorus as in II and IV, and the res- onance at 63 1.9 ppm corresponds to that of phos- phine oxides. 7 This suggests that the uncoordinated phosphorus of IV has been oxidized to phosphine oxide. Thus, based on the spectroscopic data, struc- ture D is assigned to V.

Attempts to synthesize fuc-(CO)3M(P2NJ via the interaction of (C0)3M(CH3CN)3 with 1 equi- valent of P2N2 were unsuccessful. The interaction of (C0)3M(CH3CN)3 with 1 equivalent of P2Nz gave [cis-(CO),M],(P,N,) as the only isolated prod- uct in 75% yield.

P’7

I .N

0cL40’ > oc’ 1 \u--P-o co

D

The structure of V was confirmed by X-ray crystallography. Crystals suitable for the diffraction study were grown from a mixture of CH,CI,/

Interaction of [cis-(CO),M],(P,N,) with P2Nz (M = Cr, MO)

Attempts to synthesize fac-(CO)3M(P2N2) from the dimeric species [cis-(CO),M](P,N,) were unsuc- cessful. When [cis-(CO),M],(P,N,) (I, M = Cr; II, M = MO) was treated with excess P2N2 in refluxed THF for 24 h [cis-(CO),M](P,N,) was recovered almost quantitatively. The formation of fac- (CO),M(P,N,) was not observed. This suggests that the formation of fuc-(CO),M(P,N,) is not derived

Fig. 1. A perspective view of the molecular structure of V. Both independent molecules are shown.

1050 WAI-KWOK

Table 1. Selected bond lengths (A) and angles (“) for V. The values for the second molecules are in square brackets

Mo( l)-P( 1)

Mo(l)_N(l) Mo( 1)-N(2) MO(~)-C(131) Mo(l)-C(141) Mo(l)-C(lSl)

P(2)--0(1) C(l)---N(1) C(2)-N(1) C(2)-C(3) C(3)-N(2) C(4)-N(2)

P(I)-MO(~)--N(1) P(l)-Mo( 1)-N(2) P(l)-Mo(l)-C(131) P(l)-MO(~)-C(141) P(l)-Mo(l)--C(l51) N( 1)-Mo( 1)-N(2) N(l)-MO(~)-C(131) N(l)-MO(~)--C(141) N(l)-MO(~)-C(151) N(2)--MO(~)-C(131) N(2~Mo(l)-C(141) N(2)-MO(~)-C(151) C(131)-MO(~)-C(141) C(131)--MO(~)-C(151) C(141)-MO(~)---C(151)

w-P(2w(41) 0( l)-P(2)-C(5 1) O(l)-P(2)-C(61) C(41)-P(2)-C(51) C(41)-P(2)-C(61) C(51)--P(2)-C(61)

2.485(3) 2.247(3) 2.325(7) 1.92(2) 1.96(2) 1.94(2) 1.484(9) 1.26(l) 1.47(l) 1.52(l) 1.48(l) 1.27(l)

78.4(3) 97.8(2) 85.5(3)

169.1(3) 95.3(3) 74.6(3) 95.4(3)

100.0(4) 172.7(4) 168.5(4) 92.3(4)

103.1(4) 83.8(4) 87.6(4) 86.9(4)

112.8(5) 111.4(5) 113.5(5) 106.7(5) 106.5(5) 105.2(6)

[2.512(3)] [2.254(3)] [2.306(8)]

11 .W')l [1.96(2)1 [1.93(2)1 [I .473(8)]

[1.26(1)1 11.48(1)1 11.54(1)1 [1.48(1)1 11.28(l)]

176.5(2)1 196.9(2)1 185.2(3)1

[169.2(3)] 198.5(4)1 [74.6(3)1 197.6(4)1

[ 100.7(3)] [173.7(3)] [171.1(4)] 192.3(3)1

[102.5(3)] 184.8(4)1 ]85.8(4)1 185.0(4)1

[113.0(4)] [113.2(5)] [112.2(5)] [103.6(5)] [107.8(5)] [106.4(5)]

from [cis-(CO),M](P,N,), The origin of the for- mation of the monomeric species ~~c-(CO)~M (P2Nz) is still unknown.

Preparation of [cis-(CO),Cr],(P,N,H,) (VI)

When C7HsCr(C0)4 was treated with 1 equi- valent of P2N2H4 in refluxed THF overnight yellow crystals of stoichiometry

1 (C0)4Cr]Z(P2N2H4) (VI)

were isolated in good yie d (78%). Compound VI exhibits three absorptions at 1992w, 1856s and 1832~s cm-’ in the IR spectrum (KBr), indicative of a cis configuration for the four terminal carbonyl groups and a singlet at $3.2 ppm in the 3 ‘P{ ‘H} NMR spectrum, indica ‘ng that the two phos-

!-I phorus atoms of the P,N, 4 ligand are coordinated and equivalent. The absorption pattern of the IR and 31P{ ‘H} spectra of VI is very similar to that of I, indicating that I and VI have similar struc-

WONG et al.

tures. Thus, based on the above spectroscopic data, structure E, shown below, is assigned to VI.

EXPERIMENTAL

Microanalysis were performed by the Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, China. IR spectra (KBr pellets) were recorded on a Hitachi 270-30 IR spectrometer ; data are given in cm- ‘. NMR spectra were recorded on a JEOL FX90Q spectrometer. Chemical shifts of ‘H NMR spectra were referenced to internal deut- erated solvents and then recalculated to TMS = 60.0 ppm. 31P NMR spectra were referenced to external 85% H3P04.

All operations were performed under nitrogen or in uacuo. All chemicals used were of reagent grade. Solvents were dried by standard procedures, dis- tilled and deaerated prior to use. Melting points were taken in sealed capillaries and are uncorrected.

C7H8Cr(C0)4,8 C7H8Mo(C0)4,8 MOM (CH3CN)3,8 P2Nz4 and P2N,H44 were prepared according to literature methods. ‘H and 3’P{1H} NMR data are given in Table 2.

Preparation of [cis-(CO),M](P,N,) (M = Cr, MO)

(1) M = Cr (I). A solution of C7H8Cr(C0)4 (0.13 g, 0.5 mmol) and P2N2 (0.15 g, 0.25 mmol) in THF (15 cm’) was stirred at room temperature for 16 h. A deep red colour solution was obtained. The sol- vent was removed in vacua to give a dark red residue. The residue was redissolved in a minimum amount of CH2C12 and chromatographed on a sil- ica gel column (2 x 15 cm) using CH2C12 as an eluant. The orange-red band obtained was con- centrated to ca 5 cm3 and then diethyl ether was added until the solution turned cloudy. The CH,Cl,/diethyl ether mixture was then cooled to - 20°C to give orange-red crystals, which were fil- tered and dried in vucuo. Yield : 0.21 g, 90% ; m.p. 192-195°C (decomposed). Found : C, 60.1; H, 3.3 ; N, 2.9. Calc. for C48H34Q8NZP2CrZ- $ZH&l,: C, 59.7 ; H, 3.6 ; N, 2.9%. IR (KBr) : v(C0) : 1996m, 1876vs, 1832s cm- ‘.

(2) M = MO (II). The procedure was similar to that of I, except C7HsMo(C0)4 (0.15 g, 0.5 mmol) and P2N2 (0.15 g, 0.25 mmol) were used. An orange

Reactivity of P2N, and P2N2H4 towards C,HsM(C0)4

Table 2. ‘H and 3’P(‘H} NMR data

Compound ‘H” Assignment 3’pb Assignment

1051

I

II

III

Iv

V

IV

8.26br, s(2) 7.45m(28) 4.04s(4) 8.1 lbr, s(2) 7.45m(28) 4.09s(4) 9.20br, s( 1) 8.33br, m(1) 6.60-7.45br, m(28) 4.23br, m( 1) 3.52br, m(2) 2.40br, m( 1) 9.15br, s(1) 8.23br, s( 1) 6.62-7.6Obr, m(28) 4.18br, m(l) 3.55br, m(2) 2.58br, m( 1) 9.47br, s(1) 8.23br, s(1) 6.62-7.56br, m(28) 4.18br, m(1) 3.55br, m(2) 2.58br, m( 1) 7.47br, m(28) 3.76br, m(4) 2.82br, m(4) 1.86br, m(2)

N=CH- 50.3s Phenyl

N(CHz) zN N=CH- 32.4s Phenyl

N(CHJ zN N=CH- of PC 49.4s N=CH-- of P - 17.0s Phenyl

NW-f,) 8

N=CH- of P 34.1s N=CH- of P - 17.3

Phenyl

N=CH- of P(0) 33.3s N=CH- of P 31.9s

Phenyl

NWJJ

Phenyl

N(CH&N PhCH,N NH

43.2s P,N&

P&z

P&z

PN,F PN2Pc

PN,P” PNzPc

PNJW PN,P@)

‘In CDCl, at 3O”C, referenced to Me,Si (SO.00). *In CDCl, at 30°C referenced to external 85% H,P04 (SO.OO), negative for upfield

shift. Abbreviations : s, singlet ; m, multiplet ; br, broad. cUncoordinated phosphorus.

band was obtained using CH1C12 as an eluant. Orange crystals were obtained from a mixture of CH,Cl,/diethyl ether. Yield: 0.23 g, 90%; m.p. 203-206°C (decomposed). Found : C, 49.1; H, 3.1; N, 2.3. Calc. for C48H3408N2P2M02 * 2CH&I, : C, 50.4 ; H, 3.2 ; N, 2.4%. IR (KBr) : v(C0) : 2000m, 1878~s 1838~s cm-‘.

Interaction of C7HgM(C0)4 with 1 equivalent of

P2N2

(1) M = Cr. A solution of &H,Cr(CO), (0.13 g, 0.5 mmol) and P2N2 (0.32 g, 0.53 mmol) in THF (15 cm’) was refluxed for 16 h. A violet-red coloured solution was obtained. The solvent was removed in vacua to give a dark purple residue. The residue was redissolved in a minimum amount of CH2C12 and chromatographed on a silica gel column (2 x 15 cm). An orange-red band and a violet-red band were

obtained when the column was eluted with CH2C12 and CH,Cl,/acetone (1 : 1) solutions, respectively. Work-up of the orange-red band gave orange-red crystals, which were identical to the dimeric species I. Yield : 0.03 g, 12%. The violet-red band was evap- orated to dryness in vacua and redissolved in ca 5 cm3 of CH2C12. Diethyl ether was added slowly to the CH2C12 solution until it turned cloudy. The CH,Cl,/diethyl ether mixture was then cooled to - 20°C to give violet-red crystals of stoichiometry (CO)&r(P,N,) * Hz0 (III). Yield : 0.28 g, 76% ; m.p. 175-178°C (decomposed). Found : C, 67.9 ; H, 4.9; N, 3.6. Calc. for C43H3403N2P2Cr*H20: C, 68.1 ; H, 4.8; N, 3.7%. IR (KBr): v(C0): 1900s 1780~s cm- ‘.

When a solution of C7H.&r(C0)4 (0.13 g, 0.5 mmol) and P2N2 (0.32 g, 0.53 mmol) in THF (15 cm3) was refluxed for 4 h, work-up of the solution following the above procedure gave I and III in

1052 WAI-KWOK

86% (0.22 g) and 5% (0.02 g) yields, respectively. (2) M = MO. A solution of C,H,Mo(CO), (0.09

g, 0.3 mmol) and P2Nz (0.19 g, 0.3 mmol) in THF (15 cm3) was refluxed for 16 h. A deep red solution was obtained. The solvent was removed in mcuo to give a dark red residue. The residue was redissolved in a minimum amount of CH2CI, and chromato- graphed on a silica gel cblumn (2 x 15 cm). An orange band and a deep red band were obtained when the column was elutdd with CH2C12 and ace- tone solution, respectively.1 Work-up of the orange band gave orange cry&#, whose IR, ‘H and 31P( ‘H} spectra were idenijical to that of II. Yield : 0.02 g, 13%. Removal of the solvent from the deep red band gave a deep req residue, which was re- dissolved in cu 5 cm3 of C?I,Cl,. Diethyl ether was added to the CH,Cl, solution slowly until it turned cloudy. The CH,Cl,/diethjl ether mixture was then cooled to -20°C to give Q.15 g deep red crystals. The 3’P(1H} NMR spectirum of the red crystals indicated that they were a 3 : 1 mixture of (CO), Mo(P2N2)*H20 (IV) aad (CO),Mo[PN,P(O)]* $ZH,C12 (V). Recrystallization of the crude mixture in CH$Zl,/diethjl ether solution gave V first then IV. Yield of IVY (based on the 31P{ 31H} spectrum of the crude mixture) : 0.11 g, 45% ; m.p. 173-176°C (decompiosed). Found: C, 64.2; H, 4.4; N, 3.4. Calc. for C43H3403N2P2M~ - HZ0 : C, 64.3 ; H, 4.5 ; N, 3.5%. IR (KBr) : v(C0) : 19OOs, 1780~s cm-‘. Yield of V [based on 31P{ ‘H} spec- trum of the crude mixture): 0.04 g, 15%; m.p. 180-184°C (decomposed). Found : C, 61.7 ; H, 4.4; N, 3.2. Calc. for C43H3404N2P2M~ * $H,Cll: C, 62.0; H, 4.,2; N, 3.3%. IR (KBr): v(C0) : 19OOs, 1780~s cm- ‘.

Preparation of [cis-(CO),Cr11(P1N2) (VI)

A solution of C7HsCr@Z0)4 (0.26 g, 1.0 mmol) and PzNz (0.64 g, 1.06 m 01) in THF (20 cm3) was

$ refluxed for 20 h. A ye1 w solid precipitate was obtained. The precipitate was filtered, washed with hexane (2 x 10 cm3) and

‘: dissolved in CH2C12 (20

cm’) to give a yellow sol tion. Hexane was added slowly to the CH2C12 solution until it turned cloudy. The CH,Cl,/hexane mix/ture was then cooled to -20°C to give yellow drystals of stoichiometry

KW4CMP2NJ 0’1). ‘ield: 0.36 g, 77%; m.p. 207-210°C (decomposed . Found : C, 61.4; H, 4.3 ;

F N, 2.8. Calc. for C4*H3 8N2P2Cr2: C, 61.5; H, 4.1; N, 3.0%. IR (KBr : v(C0) : 1992w, 1856.~ 1832~s cm- ‘.

Interaction of Z with P2N2

A solution of I(O.1 g, Q.l mmol) and P,N, (0.08 g, 0.13 mmol) was stirred and refluxed in THF (15

WONG et al.

cm’) for 20 h. The resultant solution was evap- orated to dryness, redissolved in a minimum amount of CH2C12 and chromatographed on a silica gel column (2 x 15 cm). An orange-red band was obtained using CHzClz as an eluant. No other colour band was obtained. Removal of the solvent from the orange-red band gave an orange-red resi- due, whose IR spectrum was identical to that of I.

Interaction of (C0)3Mo(CH3CN)3 with P2N2

A solution of (CO),Mo(CH,CN), (0.23 g, 0.76 mmol) and P,N2 (0.46 g, 0.76 mmol) in THF (15 cm-‘) was stirred at room temperature for 4 h. A red solution was obtained. The solution was evapor- ated to dryness in uacuo, redissolved in a minimum amount of CH2C12 and chromatographed on a silica gel column (2 x 15 cm) using CHzClz as an eluant. The orange band obtained was concentrated to ca 5 cm3 and then diethyl ether was added until the solution turned cloudy. The CH&l,/diethyI ether mixture was then cooled to -20°C to give orange crystals, whose IR spectrum was identical to that of II. Yield : 0.29 g, 75%.

X-ray diflraction studies

Crystals of V suitable for X-ray diffraction study were grown from CH,Cl,/n-hexane as a solvate of stoichiometry V* !CH,Cl,. A dark red crystal of dimensions 0.17 x 0.22 x 0.25 mm3 was mounted on a glass fibre with an epoxy resin. Intensity data were collected on an Enraf-Nonius CAD-4 diffrac- tometer at room temperature, using graphite mono- chromated MO-& radiation (A = 0.71073 A). 11,385 reflections (28 < 45”) were measured ; 10,993 were unique, Rint = 0.024, and of these 7406 had I > 30(I) and were considered to be observed. The data were collected for Lorentz and polarization factors, but no absorption correction was applied. Crystal data, data collection parameters and results of the analysis are given in Table 3. The structure was solved by a combination of Patterson and direct methods (DIRDIF).’ Two crystallographic inde- pendent molecules of V and a partially occupying solvent molecule of CH2C12 were located in the asymmetric unit. All non-carbon, non-hydrogen atoms, except for the solvent molecule, were refined anisotropically. The hydrogen atoms were gener- ated in their idealized positions (C-H bond fixed at 0.96 A) and included in structurefactor cal- culations, but not in refinement. Refinement was by full-matrix least-squares. All calculations were carried out on a MicroVAC-II computer using the Enraf-Nonius SDP program. lo Final atomic coor- dinates, thermal parameters and structure factors

Reactivity of P2Nz and P2NIH, towards C,HsM(CO),

Table 3. Data collection and processing parameters

1053

Molecular formula Molecular weight Colour and habit Unit cell parameters

a (A”) b (A”) c (A”) V (A”) B (“) Z Density (talc.) (g cn- ‘) Space group Radiation Absorption coefficient (cm- ‘) Crystal size (mm’) Scan type and rate (” min- ‘) Scan range Collection range Unique data measured Observed data with Z > 30(Z), II Number of variables, p

R = EllFol -l~cll/Wol R, = PWcoI - I~cI)zIW~o121”2 Weighting scheme

s = [=4l~ol - IF,l)*/(~-P)l”* Residual extrema in final difference map (e A- ‘)

[Mo(C&,H~~N~OP~)(CO)~] - 0.25CH2C12 821.89 Dark red block

18.689(4) 21.935(4) 19.954(8) 8170(2) 92.65(2) 8 1.336 P2,/c (No. 14) Graphite-monochromatized MO-K,, 1 = 0.71073 A 4.3 0.17 x 0.22 x 0.25 ~20; 1.08-8.24 0.50+0.34 tan fJ h, k, f 1; 20,,, = 45” 10,993 7406 507 0.065 0.084 w = 1/{1+[(F,-23.8)/111.9]2} 3.287 + 1.70 to -0.66

have been deposited with the Editor as sup- 4. plementary data. Atomic coordinates have also been deposited with the Cambridge Crys- 5. tallography Data Centre.

6.

Acknowledgements-W.-K. W. thanks the Hong Kong Baptist College and the UPGC (Hong Kong) for financial support. W.-T. W. thanks the Hong Kong Research 7. Grant Council and the University of Hong Kong for financial support.

8.

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