Synthesis and spectral characterization of bis(β-diketonato)zirconium(IV) and -hafnium(IV) phthalocyaninates

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Synthesis and spectral characterization of bis(β-diketonato)zirconium(IV) and -hafnium(IV) phthalocyaninates

L.A. Tomachynski, V. Ya. Chernii*, S.V. Volkov

Institute of General and Inorganic Chemistry, Prospect Palladina 32/34, Kiev, Ukraine

Received 23 September 2001Accepted 16 November 2001

ABSTRACT: The reaction of PcMCl2 (M = Zr, Hf) with β-diketones is reported. 1H NMR and elemental analysis suggest the substitution of two Cl atoms for two β-diketone fragments takes place as a result of this reaction and the complexes PcM(β-dik)2 are formed. All obtained complexes are stable and highly soluble in most organic solvents. The data from 1H and 19F NMR, and UV-vis spectroscopy suggest the coordination of two β-diketone ligands in a cis geometry about the central atom of the macrocycle. It was shown bis(β-diketonato)zirconium(IV) and hafnium(IV) phthalocyanines containing β-diketones with donor or acceptor groups or with bulky substituents can be obtained. Copyright © 2002 Society of Porphyrins & Phthalocyanines.

KEYWORDS: axial substitution, zirconium(IV) and hafnium(IV) phthalocyanines, β-diketones, synthesis.

INTRODUCTIONPhthalocyanine and porphyrin derivatives

have attracted attention because of their unique electronic, optical, and structural properties which offer applications in various fields of science and engineering such as nonlinear optics [1], catalysis [2], liquid crystals [3], electronics [4, 5], sensors [6], photosensitizers [7] and semiconductor devices [8, 9]. Mixed ligand phthalocyanine complexes are the most interesting for studying the spectroscopic and electrochemical properties of these compounds. Among them, bis(β-diketonato)thorium(IV) and –uranium(IV) phthalocyanines have attracted special attention [10-12]. At the same time, phthalocyanine complexes of the Group IV d-elements which contain axially coordinated β-diketones have not been sufficiently investigated. However, the introducing of axially coordinated ligands to the central metal atom can have a significant influence on the π-electron conjugation of the macromolecule. In particular, such axial substitution can alter the

electronic structure of phthalocyanine as well as change the spatial relationships between neighboring molecules via steric effects and thus the magnitude of the intermolecular interactions. Each of these effects can influence the compound’s photo- and semi- conductive and non-linear optical properties.

In a previous work [13] we showed that dichloro-(phthalocyaninato)zirconium (IV) and hafnium(IV) react easily with 2,4-pentadione. In this case bis(acetilacetonato)zirconium(IV) and –hafnium(IV) phthalocyanines were obtained.

We found by elemental analysis and 1H NMR spectroscopy that two acac fragments were coordinated to the central metal-atom of the macrocycle as shown in equation (1).

PcMCl2 + 2 acac " PcM(acac)2 + 2 HCl (1)

The UV-vis spectroscopy data allowed suggested a cis arrangement of the two acac ligands about the metal in the PcM(acac)2 complex.

The aim of this work was to study the reaction of substitution of Cl ions at the central metal-atom (Zr, Hf) of the macrocycle for different β-diketones (Fig. 1) and subsequently to synthesize

*Correspondence to: V. Ya. Chernii, email: [email protected]

Journal of Porphyrins and Phthalocyanines Published at http://www.u-bourgogne.fr/jpp/

J. Porphyrins Phthalocyanines 2002; 6: 114-121

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bis(β-diketonato)zirconium(IV) and –hafnium(IV) phthalocyanines (PcZr(β-dik)2, PcHf(β-dik)2) and to investigate their spectroscopic properties. The obtained compounds were characterised by UV-vis, 1H and 19F NMR and IR spectroscopy and by elemental analysis.

EXPERIMENTAL

Materials

IR spectra were recorded on a Specord M-80 spectrometer in KBr pellets. 1H NMR spectra were recorded on a Varian (300MHz) spectrometer (CDCl3/TMS). The UV-vis absorption spectra were obtained on a Specord M-40 in CDCl3 (path length = 1mm).

Synthesis

All reactions were carried out under atmospheric conditions (Fig. 2). Toluene, hexane and CHCl3 were used without further purification; β-diketones (Fig. 1) were used as received. Initial dichloro-(phthalocyaninato) zirconium(IV) and hafnium(IV) were prepared by the reaction of ZrCl4 (HfCl4) with

phthalodinitrile following published procedures [14] with minor modifications [15].

Synthesis of bis(β-diketonato)zirconium(IV) and –hafnium(IV) phthalocyanines: general procedure. A 0.74 mmol sample of PcMCl2 was suspended in 10 ml of toluene, and 1.67 mmol β-diketone was added. The reaction mixture was heated at 116 °C for 3-6 hours under reflux (evolution in HCl). The hot solution was filtered for separation from the starting materials. The resulting solution was cooled to room temperature and the formed crystals of the metal bis(β-diketonato)phthalocyanine complex were isolated and washed abundantly with hexane. Hexane was added to the solution if it was necessary. All synthesized complexes were first air-dried, and after that dried in vacuum at 60 °C for 8 h. Time of the reaction and total yield are given in the Table 1. Satisfactory elemental analysis data (C ± 0.90, H ± 0.50, N ± 0.70, M ± 0.30) were obtained.

Elemental analysis data: 1a: Calc. C = 62.90%, H = 3.77%, N = 13.97%, Zr = 11.37%, Found C = 62.50%, H = 3.75%, N = 13.45%, Zr = 11.52%; 1b: Calc. C = 56.73%, H = 3.40%, N = 12.60%, Hf = 20.07%, Found C = 56.65%, H = 3.25%, N = 12.10%, Hf = 20.15%; 2a: Calc. C = 64.39%, H = 4.46%, N = 13.06%, Zr = 10.63%, Found C = 64.30%, H = 4.15%,

Fig. 1. List of β-diketones


BIS-(β-DIKETONATO)ZIRCONIUM(IV) AND -HAFNIUM(IV) PHTHALOCYANINATES

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Fig. 2. Synthesis of the axially substituted metal phthalocyanine complexes with β-diketonate ligands

Table 1. The data of time and yield of reactions

Pc-complex MAxial ligand

Time, h Yield, %R’ R”

1a Zr CH3 CH3 3 54

1b Hf CH3 CH3 3 66

2a Zr CH3 n-C3H7 5 57

2b Hf CH3 n-C3H7 4 49

3a Zr CH3 n-C6H13 6 66

3b Hf CH3 n-C6H13 5 68

4a Zr CH3 n-C7H15 6 60

4b Hf CH3 n-C7H15 5 57

5a Zr CF3 CH3 2.5 49

5b Hf CF3 CH3 2 43

6a Zr CF3 CF3 1.5 55

6b Hf CF3 CF3 1 68

7a Zr CF3 C(CH3)3 4 68

7b Hf CF3 C(CH3)3 4 70

8a Zr CF3 CH(C2H5)2 2.5 50

8b Hf CF3 CH(C2H5)2 2 41

9a Zr CF3 C(OCH3)(CH3)2 3 71

9b Hf CF3 C(OCH3)(CH3)2 3 66

10a Zr CF3 C6H5 2.5 49

10b Hf CF3 C6H5 2 67

11a Zr CH3 C6H5 4.5 44

11b Hf CH3 C6H5 4.5 47

12a Zr C(CH3)3 n-C3F7 3 62

12b Hf C(CH3)3 n-C3F7 2.5 64

13a Zr C(CH3)3 C(OCH3)(CH3)2 4 64

13b Hf C(CH3)3 C(OCH3)(CH3)2 4 67


L.A. TOMACHYNSKI ET AL.

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N = 12.65%, Zr = 10.80%; 2b: Calc. C = 58.44%, H = 4.05%, N = 11.85%, Hf = 18.88%, Found C = 58.05%, H = 3.85%, N = 11.90%, Hf = 18.90%; 3a: Calc. C = 66.29%, H = 5.35%, N = 11.89%, Zr = 9.68%, Found C = 66.85%, H = 5.80%, N = 12.05%, Zr = 9.70%; 3b: Calc. C = 60.67%, H = 4.90%, N = 10.88%, Hf = 17.34%, Found C = 61.00%, H = 5.15%, N = 11.05%, Hf = 17.40%; 4a: Calc. C = 66.85%, H = 5.61%, N = 11.55%, Zr = 9.40%, Found C = 66.10%, H = 5.25%, N = 11.05%, Zr = 9.45%; 4b: Calc. C = 61.33%, H = 5.15%, N = 10.60%, Hf = 16.88%, Found C = 61.70%, H = 5.10%, N = 10.20%, Hf = 16.90%; 5a: Calc. C = 55.44%, H = 2.66%, N = 12.31%, Zr = 10.03%, Found C = 55.05%, H = 2.60%, N = 11.80%, Zr = 9.85%; 5b: Calc. C = 50.59%, H = 2.43%, N = 11.24%, Hf = 17.90%, Found C = 51.30%, H = 2.55%, N = 10.90%, Hf = 17.70%; 6a: Calc. C = 49.56, H = 1.78%, N = 11.01, Zr = 8.96, Found C = 48.90%, H = 1.50%, N = 11.25%, Zr = 8.80%; 6b: Calc. C = 45.65%, H = 1.64%, N = 10.14%, Hf = 16.15%, Found C = 45.05%, H = 1.60%, N = 10.20%, Hf = 16.05%; 7a: Calc. C = 58.00%, H = 3.65%, N = 11.27%, Zr = 9.18%, Found C = 57.30%, H = 3.40%, N = 10.65%, Zr = 9.20%; 7b: Calc. C = 53.32%, H = 3.36%, N = 10.36%, Hf = 16.51%, Found C = 53.60%, H = 3.05%, N = 9.90%, Hf = 16.50%; 8a: Calc. C = 58.76%, H = 3.94%, N = 10.96%, Zr = 8.92%, Found C = 58.50%, H = 3.60%, N = 11.05%, Zr = 8.95%; 8b: Calc. C = 54.13%, H = 3.63%, N = 10.10%, Hf = 16.09%, Found C = 54.65%, H = 3.75%, N = 10.25%, Hf = 16.10%; 9a: Calc. C = 56.19%, H = 3.54%, N = 10.92%, Zr = 8.89%, Found C = 55.35%, H = 3.05%, N = 10.25%, Zr = 8.85%; 9b: Calc. C = 51.78%, H = 3.26%, N = 10.06%, Hf = 16.03%, Found C = 51.15%, H = 2.95%, N = 9.55%, Hf = 16.15%; 10a: Calc. C = 60.40%, H = 2.73%, N = 10.84%, Zr = 8.82%, Found C = 60.05%, H = 2.65%, N = 10.35%, Zr = 8.55%; 10b: Calc. C = 55.70%, H = 2.52%, N = 9.99%, Hf = 15.92%, Found C = 55.20%, H = 2.15%, N = 10.15%, Hf = 15.85%; 11a: Calc. C = 67.44%, H = 3.70%, N = 12.10%, Zr = 9.85%, Found C = 67.75%, H = 3.45%, N = 11.80%, Zr = 9.70%; 11b: Calc. C = 61.63%, H = 3.38%, N = 11.06%, Hf = 17.61%, Found C = 61.50%, H = 3.05%, N = 10.75%, Hf = 17.55%; 12a: Calc. C = 52.30%, H = 3.04%, N = 9.38%, Zr = 7.64%, Found C = 51.85%, H = 3.35%, N = 9.50%, Zr = 7.60%; 12b: Calc. C = 48.74%, H = 2.83%, N = 8.74%, Hf = 13.93%, Found C = 48.95%, H = 2.90%, N = 8.45%, Hf = 13.90%; 13a: Calc. C = 64.71%, H = 5.73%, N = 11.18%, Zr = 9.10%, Found C = 64.05%, H = 5.30%, N = 10.75%, Zr = 9.05%; 13b: Calc. C = 59.53%, H = 5.00%, N = 10.28%, Hf = 16.38%, Found C = 59.05%, H = 5.15%, N = 9.80%, Hf = 16.50%.

RESULTS AND DISCUSSIONAll synthesized compounds are fine crystalline

substances that dissolve in most organic solvents (benzene, toluene, chloroform and others), in contrast to the starting complexes.

The high stability of the starting bis(chloro)phthalo-cyanine complexes allow synthesis of the β-diketonate complexes by a direct interaction of the components (Fig. 2). 1H NMR and elemental analysis suggest that the two β-diketonate ligands are coordinated to the central atom of the macrocycle. It has been established that the presence of an HCl acceptor (pyridine, triethylamine) does not influence the rate of the reaction or the yield of the products. The use of solvents with lower boiling temperatures leads to an increase in the reaction time, a decrease in the product yield and a decreased reproducibility of the results. In the case of the reaction between bis(chloro)zirconiumphthalocyanine and methoxypivaloylmethane (ligand 13 in Fig. 1) in benzene a complex with the ratio phthalocyanine : β-diketone = 1:1 has been obtained as indicated by the NMR data. The 1:2 phthalocyanine : β-diketone complex has been synthesized by the same reaction in toluene.

The IR spectra of each synthesized complex exhibits vibrational bands typical of the phthalocyanine ligand. Two moderately strong absorptions in the far-IR region at 350-250 cm-1 assigned to the symmetric and antisymmetric M–Cl modes are absent. The bands near 1620-1500 cm-1 which can be assigned to the ν(C=O) and ν(C =C) frequencies appear. Such bands are typical for the carbonyl group conjugated with double carbon – carbon bond in the enol form of β-diketones. That is to say the chelating rings with equivalent C–O and C–C bond are formed (Table 2). In the case of phthalocyanine complexes with fluorine containing β-diketonate ligands (ligands 5-10 and 12 in Fig. 1), the absorptions in the range 1300-1200 and 1180-1110 cm-1 appear. These bands can be assigned to the antisymmetric and symmetric stretching vibrations of the bond of the corresponding CF3 group. The bands at 3100-2800 cm-1 for all complexes except 6a, 6b, 8a, 8b we assign to the symmetric and antisymmetric stretching vibrations of the alkyl substitutes in the β-diketonate fragments. Absorptions due to the metal-oxygen vibration are located at 550-450 cm-1 for all complexes. The presence of these absorption peaks in the low-frequency region provides evidence for the formation of the pseudoaromatic rings.

1H and 19F NMR spectra of all synthesized complexes, β-diketones, and tetra(β-diketonato)zirconium(IV) and hafnium(IV) were recorded in CDCl3 under the same conditions. The resonance positions and the morphology of the AA’BB’ multiplets of the phthalocyanine



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Fig. 3. 1H NMR spectrum of PcZr(CH3COCH2COC6H13)2 in CDCl3

Table 2. Spectroscopic characteristic of synthesized complexes

N IR, νC=O, C=C, cm-1 UV-vis, λ, nm (log ε)

1a 1600, 1575, 1540, 1510 344.6(4.78), 617.2(4.58), 684.9(5.29), 688.1(5.29)

1b 1610, 1585, 1570, 1540, 1510 340.9(4.82), 616.7(4.61), 684.2(5.37), 686.8(5.38)

2a 1605, 1595, 1570, 1530, 1508 340.7(4.75), 616.1(4.42), 685.5(5.16)br

2b 1602, 1595, 1580, 1530, 1508 342.7(4.79), 615.5(4.48), 680.6(5.21)sh, 687.8(5.23)

3a 1602, 1592, 1575, 1567sh, 1531, 1507 340.7(4.85), 616.1(4.52), 681.6(5.25)sh, 688.9(5.27)

3b 1605, 1593, 1578, 1570, 1530, 1506 334.5(4.78), 618.2(4.42), 684.1(5.22)sh, 686.2(5.24)

4a 1630, 1615sh, 1595, 1532, 1510 335.4(5.10), 618.4(4.70), 686.3(5.45)sh, 687.9(5.46)

4b 1637, 1610, 1597, 1540, 1510 339.1(4.98), 616.9(4.67), 684.4(5.44)sh, 685.8(5.45)

5a 1639, 1619, 1600sh, 1537, 1509 346.1(4.71)sh, 617.1(4.37), 685.6(5.11), 691.7(5.07)sh

5b 1635, 1620, 1600sh, 1539, 1509 349.0(4.58), 617.9(4.26), 683.4(5.38)sh, 692.2(5.40)

6a 1700sh, 1685, 1662, 1650, 1612, 1600sh 336.1(4.63), 618.8(4.29), 682.2(5.00), 689.4(5.05)

6b 1680sh, 1663, 1660, 1610, 1600sh 345.0(4.74)sh, 619.4(4.40), 682.1(5.08), 693.3(5.09)

7a 1660sh, 1636, 1624, 1602, 1548, 1522, 1509 340.9(4.72), 617.2(4.45), 682.0(5.20)sh, 686.7(5.21)

7b 1650sh, 1639, 1623, 1602, 1543, 1520, 1508 340.9(4.90), 616.7(4.58), 682.8(5.34)sh, 687(5.35)

8a 1631, 1615, 1600sh, 1520sh, 1509 346.5(4.74)sh, 616.6(4.42), 680.4(5.15)sh, 689.4(5.16)

8b 1635, 1615, 1600sh, 1530sh, 1511 338.9(4.72), 615.0(4.41), 678.8(5.12)sh, 688.9(5.13)

9a 1640sh, 1628sh, 1612, 1600sh, 1575, 1529, 1508 335.5(4.94), 618.4(4.60), 685.8(5.35), 687.0(5.36)

9b 1640sh, 1623sh, 1612, 1600sh, 1580, 1528, 1510 334.2(4.87), 615.3(4.49), 654.2(4.43), 684.4(5.25)

10a 1625sh, 1615, 1600, 1578, 1570sh, 1543, 1508 345.5(4.84)sh, 618.6(4.45), 684.1(5.16)sh, 691.9(5.18)

10b 1635, 1609, 1599, 1565sh, 1542, 1507 349.0(4.83), 617.9(4.48), 683.4(5.19)sh, 692.2(5.21)

11a 1605sh, 1592, 1552, 1530sh, 1522, 1510sh 342.8(4.58), 618.2(4.30), 686.4(5.13)br

11b 1600sh, 1592, 1555, 1535sh, 1525, 1510sh 342.8(4.53), 616.9(4.27), 684.9(5.17)

12a 1640sh, 1632, 1613, 1605, 1545, 1511 339.9(4.73), 616.6(4.43), 682.6(5.19)sh, 688.9(5.21)

12b 1645sh, 1635, 1617, 1605sh, 1545, 1511 343.3(4.76), 615.6(4.43), 680.6(5.15)sh, 688.3(5.17)

13a 1615sh, 1590, 1570, 1550sh, 1510 341.7(4.80), 617.1(4.52), 654.7(5.28)sh, 685.0(5.31)

13b 1605sh, 1590, 1568, 1550sh, 1509, 1499sh 337.1(4.87), 616.3(4.61), 683.7(5.57)sh, 685.6(5.57)



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Table 3. The 1H NMR data

N°

σ, ppm

Pc-ligand β-diketone ligands

Hα(m.,8H) Hβ(m.,8H) -CH= -CH2-, -CH3, -C6H5

1a 9.46 8.16 4.25s. 1.23 (12H, s., -CH3)

1b 9.47 8.18 4.19s. 1.19 (12H, s., -CH3)

2a 9.44 8.13 4.20d. 1.59, 1.31 (each 2H, m., -CH2-), 1.21, 1.15 (each 3H, s., -CH3), 0.88, 0.75 (each 2H, m., -CH2-), 0.44, 0.37 (each 3H, t., -CH3).

2b 9.44 8.14 4.15d. 1.53, 1.27 (each 2H, m., -CH2-), 1.19, 1.12 (each 3H, s., -CH3), 0.86, 0.71 (each 2H, m., -CH2-), 0.41, 0.37 (each 3H, t., -CH3).

3a 9.43 8.12 4.19d. 1.54, 1.28 (each 2H, m., -CH2-), 1.20, 1.14 (each 3H, s., -CH3), 1.04, 0.93 (10H, m., -C6H13), 0.79 (12H, m., -C6H13 ).

3b 9.43 8.14 4.14d. 1.54, 1.27 (each 2H, m., -CH2-), 1.18, 1.12 (each 3H, s., -CH3), 1.04 (11H, m., -C6H13), 0.79 (12H, m., -C6H13 ).

4a 9.46 8.21 4.12d. 1.54, 1.28 (each 2H, m., -CH2-), 1.12 (6H, s.,-CH3), 0.85 (11H, m., -C6H13 ), 0.62 (8H, m., - C6H13), 0.35 (4H, m.,-C6H13), 0.10 (4H,m.,- C6H13).

4b 9.28 8.05 4.09d.1.20, 1.14 (each 3H, s., -CH3),1.08 (4H, m.,-C6H13), 0.78 (10H, m., -C6H13), 0.57 (4H, m., -C6H13 ), 0.44 (4H, m., -C6H13 ), 0.25 (4H, m., -C6H13), 0.05 (4H, m., -C6H13).

5a 9.46 8.19 4.57d. 1.36 (6H, d., -CH3).

5b 9.37 8.13 4.44d. 1.19 (6H, d., -CH3).

6a 9.25 8.11 4.70s.

6b 9.17 8.10 4.60s.

7a 9.31 8.10 4.60d. 0.45 (18H, d., -C(CH3)3).

7b 9.34 8.13 4.51d. 0.34 (18H, d., -C(CH3)3).

8a 9.34 8.12 4.50d. 1.08 (2H, q., -CH=), 0.88, 0.69 (each 4H, m.,-CH2), 0.42, 0.36 (each 6H, t., -CH3), 0.27, 0.08 (each 6H, t., -CH3).

8b 9.34 8.12 4.44d. 1.07 (2H, q., -CH=), 0.91, 0.68 (each 4H, m.,-CH2), 0.36, 0.32 (each 6H, t., -CH3), 0.27, 0.12 (each 6H, t., -CH3).

9a 9.24 8.18 4.76d. 2.18 (6H, s., -OCH3), 0.87, 0.12 (each 6H, t., -CH3).

9b 9.14 8.01 4.77d. 2.38 (6H, s., - OCH3), 0.88, 0.02 (each 6H, t.,-CH3).

10a 9.27 8.21 5.52d. 7.56 (2H, q., -C6H5), 7.25 (4H, q., -C6H5), 6.96 (4H, t., -C6H5).

10b 9.37 8.02 5.06d. 7.39 (2H, q., -C6H5), 7.08 (4H, q., -C6H5), 6.65 (4H, t., -C6H5).

11a 9.66-9.02

8.28-7.96 4.97d. 7.41 (2H, q., -C6H5), 7.16 (4H, q., -C6H5), 6.87 (4H, t., -C6H5), 1.40 (6H,

s., -CH3).

11b 9.61-9.04

8.28-7.99 4.92d. 7.40 (2H, q., -C6H5), 7.13 (4H, q., -C6H5), 6.85 (4H, t., -C6H5), 1.36 (6H,

s., -CH3).

12a 9.39 8.14 4.64d. 0.47 (18H, s., -C(CH3)3).

12b 9.38 8.15 4.60d. 0.46 (18H, s., -C(CH3)3).

13a 9.65 8.42 5.01d. 2.83 (6H, q., -OCH3), 1.40 (3H, q., -CH3), 0.78 (18H, m., - C(CH3)3), 0.46 (3H, q., -CH3).

13b 9.69 8.51 5.07d. 2.90 (6H, q., -OCH3), 1.52 (3H, q., -CH3), 0.89 (18H, m., - C(CH3)3), 0.54 (3H, q., -CH3).



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ring protons (Fig. 3) are similar to those of other metallophthalocyanines [12,16]. The signals of the axial ligand protons are shifted upfield by the phthalocyanine ring current (Table 3). 1H NMR spectra of the zirconium and hafnium phthalocyanine complexes with β-diketones show that the metal atom does not have a significant influence on the resonance position and the morphology of the signals of the ring and axial ligand protons. At the same time, the signals of the β-diketonate ligand protons are shifted upfield by comparison with the free β-diketones and M(β-dik)4. The signal of the methine group proton of the axial ligands in PcZr(β-dik)2 and PcHf(β-dik)2 is located near 4.00 – 5.50 ppm in contrast with free β-diketones and tetra(β-diketonato)zirconium(IV) which is located at about 6.00-6.20 ppm. For example, the 1H NMR spectrum complex 12a (or 12b) shows the eighteen protons of the two tert-butyl groups give a signal at 0.47 (or 0.46) ppm whereas the protons of the tert-butyl group in free 6,6,7,7,8,8,8-heptafluoro-2,2-dimethyl-3,5-octanedione and tetra(6,6,7,7,8,8,8-heptafluoro-2,2-dimethyl-3,5-octanedionato)zirconium(IV) give a signal about 1.24 ppm for both complexes (Fig. 4). In our opinion, the ligand plane and the phthalocyanine plane form the acute angle. In this way the tert-butyl group protons are in the magnetic anisotropy cone of phenyl fragment of the phthalocyanine macrocycle. These spectroscopic properties give evidence that two β-diketone ligands are coordinated in the cis- geometry about the central atom of the macrocycle.

In the case of the complexes with the symmetric β-diketonate ligands 1 and 6 (Fig. 1) the signal of the methine group proton is a singlet. Complexes with asymmetric β-diketonate ligands show more complicated 1H NMR spectra. In particular the signal of the methine group proton is split indicating a non-equivalence of methine protons in the complexes. The question about the coordination of the β-diketonate axial ligands concerning each other appears. We can conclude that a mixture of A and B isomers forms (Fig. 5), β-diketonate axial ligands being coordinated

Fig. 4. 1H NMR spectra of (a) 6,6,7,7,8,8,8-heptafluoro-2,2-dimethyl-3,5-octanedione, (b) Zr((CH3)3CCOCHCOC3F7)4 and (c) PcZr((CH3)3CCOCHCOC3F7)2 in CDCl3

Fig. 5. Coordination of the β-diketonate ligands about the central atom of the macrocycle



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in a cis or trans configuration in the isomers, correspondingly. In this case, the integral intensity of the signals of the methine protons distributes with a ratio from 1:1 to 2:3. The reaction is not selective and a non-statistic mixture of the structure A and B forms. The 19F spectra of complex 8a and 10a show two kinds of signals which have an integral intensity with ratio 2:3 that confirms the formation of the non-statistic mixture.

The electronic absorption spectra of the synthesized complexes show typical patterns of metal phthalocyanine complexes with characteristic B- and Q- bands at 330-350 and 680-690 nm respectively (Fig. 6). The splitting of the Q-band in the UV-vis spectra of the phthalocyanines 1a, 1b, 6a, and 6b is observed. The Q-band of the phthalocyanines with ligands 2-5, 7, 8, 10-13 is broad and non-split. It can be explained by a superposition of the structures A and B. This behavior is attributed to a decrease in the symmetry of the molecule. It also proves the cis-coordination geometry for the metal-chelate group.

CONCLUSIONThe reaction of PcMCl2 (M = Zr, Hf) with

β-diketones is described the first time. The new phthalocyaninato zirconium and hafnium complexes containing axially coordinated β-diketonate ligands were synthesized. It was determined that the coordination of two β-diketone ligands in a cis configuration about the macrocycle plane takes place. In the case of complexes containing the antisymmetric β-diketonate ligands, formation a mixture of the two isomers, in which the substituents of the β-diketonate axial ligands are cis and trans coordinated one to another, is observed. It was shown bis(β-diketonato)zirconium(IV) and hafnium(IV) phthalocyaninates containing β-diketones with donor or acceptor groups or with bulky substituents can be obtained.

Acknowledgments

We are grateful to Dr. V. V. Pirozhenko for help in recording of the 1H and 19F NMR spectra.

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Fig. 6. UV-vis spectra of (a) PcZr(CF3COCH2COCF3)2, (b) PcZr(CF3COCH2COCH3)2.



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Copyright of the works in this Journal is vested with World Scientific Publishing. Thearticle is allowed for individual use only and may not be copied, further disseminated, orhosted on any other third party website or repository without the copyright holder’swritten permission.

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Documents

Synthesis and spectral characterization of bis(β-diketonato)zirconium(IV) and -hafnium(IV) phthalocyaninates