Adducts of Zinc Complexes
Inorganic Chemistry, Vol. 39, No. 7, 2000 1579
Zn(O-2,6-tBu2C6H3)2(PCy3) (2). Crystals of 2 were grown from the
concentrated toluene solution overnight at 0 °C, providing 0.19 g (54%)
of the product. Anal. Calcd for ZnC46H75O2P: C, 72.6; H, 9.88.
Found: C, 73.1; H, 9.90. 1H NMR (C6D6): δ 0.8-2 (m, 33H, PC6H11),
1.77 (s, 18H, CCH3), 6.81 (t, 2H, p-C6H3). 13C NMR (C6D6): δ 27.6-
32 (PC6H11), 32.5, 165.2 (ipso C6H3). 31P NMR (C6D6): δ 7.74.
Zn(O-2,6-tBu2C6H3)2(PMe3) (3). After the volatiles were removed
under vacuum, the material was washed twice with cold hexanes,
resulting in a white powdery solid in 47% isolated yield. 1H NMR: δ
0.252 (d, JP-H ) 8.7 Hz, PCH3), 1.66 (s, 18H, CCH3), 6.81 (t, 2H,
phosphine derivatives of zinc are rather rare with most
investigations focusing on 31P NMR studies of phosphine
derivatives of zinc halides.15,16 Crystallographically characterized
examples are limited to the chemical vapor deposition (CVD)
candidates Zn(S-2,4,6-tBuC6H3)2(Ph2PMe),17 (Et2NCS2)2Zn-
(PMe3),18 and the zinc halide structure [ZnI2(PEt3)]2.19 Herein,
we present the synthesis, solid-state, and solution structures of
phosphine adducts of active catalysts for the copolymerization
of cyclohexene oxide and CO2, (bisphenoxide)zinc complexes.20
p-C6H3), 7.33 (d, 4H, m-C6H3). 13C NMR (C6D6): δ 10.95 (d, JP-C
)
Experimental Section
24.2 Hz), 30.36 (CCCH3), 31.77(CCH3), 115.89, 125.29, 138.82, 165.33
(ipso-C6H3). 31P NMR (C6D6): δ -48.9.
Methods and Materials. All syntheses and manipulations were
carried out on a modified Schlenk line or in a glovebox under argon.
Glassware was flamed out thoroughly before use. Toluene, hexane, and
benzene were freshly distilled from sodium benzophenone, and
dichloromethane was distilled from P2O5 prior to their use. Diphenyl-
methylphosphine and bisdicyclohexylphosphinomethane were purchased
from Strem and stored in a glovebox. Trimethylphosphine was
purchased from Strem and stored in a Schlenk tube under an atmosphere
of argon. Triethylphosphine and tricyclohexylphosphine were purchased
from Aldrich and were stored in a glovebox. Tri-n-butylphosphine
(>90% purity) was purchased from Aldrich packaged as a sure-seal
container and was stored under argon atmosphere. All phosphines were
used without further purification. The phenols 2,6-di-tert-butylphenol,
2,6-diphenylphenol, 2,4,6-trimethylphenol, and 2,4,6-tri-tert-butylphenol
were all purchased from Aldrich. The 2,4,6-tri-tert-butylphenol is very
hygroscopic and was purified by means of sublimation in vacuo before
use (bath temperature ca. 100 °C, 3.5 mmHg). Zn[N(SiMe3)2]2 was
prepared according to the published procedure and isolated through
distillation in vacuo as a clear, slighty viscous liquid (bp ) 103-104
°C, 4 mmHg).16 This material is extremely moisture-sensitive and, as
such, was stored in a glovebox and used immediately after removal
from the box. 31P NMR data were acquired on Varian XL200 and
Unity+ 300 MHz superconducting NMR spectrometers operating at
81 and 121 MHz, respectively. Both instruments are equipped with
variable-temperature control modules. All 31P NMR data are referenced
Zn(O-2,6-tBu2C6H3)2(PEt3) (4). A microcrystalline material grew
from a toluene solution that had been concentrated down to about 2
1
mL. The final yield after drying was 0.11 g (37%). H NMR (C6D6):
δ 0.98 (m, 9H, PCH2CH3), 1.22 (m, 6H, PCH2CH3), 6.92 (t, 2H,
p-C6H3), 7.37 (d, 4H, m-C6H3). 31P NMR (C6D6): δ -14.0.
Zn(O-2,6-tBu2C6H3)2(PBu3) (5). A white powdery solid (0.137 g,
81% yield) was left behind after the material was washed twice in cold
1
hexanes. H NMR (C6D6): δ 0.67-1.23 (m, 9H, PBu), 1.72 (s, 18H,
CCH3), 6.803 (t, 2H, p-C6H3), 7.33 (d, 4H, m-C6H3). 13C NMR
(C6D6): δ 13.42, 20.64 (d, PCH2), 24.34, 24.52, 115.74, 125.09, 138.70,
165.09 (ipso-C6H3). 31P NMR (C6D6): δ -21.0.
Synthesis of [Zn(O-2,6-tBu2C6H3)2]2(PCy2)2CH2 (6). Bisdicyclo-
hexylphosphinomethane (0.1 g, 0.000 25 mol) and 2,6-di-tert-butyl-
phenol (0.206 g, 0.0005 mol) were dissolved in 5 mL of toluene. The
toluene solution was then added to neat Zn[N(SiMe3)2]2 and was stirred
for 0.5 h. The volatiles were then stripped away in vacuo, giving a
slightly yellowed fine powder in 82% yield. 31P NMR (C6D6): δ -3.77.
[Zn(O-2,6-tBu2C6H3)2]2(Me2PPh) (7). After the volatiles were
removed under vacuum, the product was washed several times with
cold hexanes to provide a white powdery solid in 52% yield. 1H NMR
(C6H6): δ 0.72 (d, PCH3), 1.64 (s, 18H, CCH3), 6.89 (t, 2H, p-C6H3),
7.37 (d, 4H, m-C6H3). 31P NMR (C6H6): δ -35.8.
Synthesis of Zn(O-2,4,6-tBu3C6H2)(PMe3)2 (8). A 5 mL toluene
solution of 2,4,6-tri-tert-butylphenol (0.33 g, 1.3 mmol) was added to
Zn[N(SiMe3)2]2 (0.25 g, 0.65 mmol) dissolved in 3 mL of toluene. After
the solution was stirred for 30 min, 1 equiv of trimethylphosphine (0.134
µL, 0.65 mmol) was added via a syringe. The mixture was stirred for
an extra 15 min and then concentrated down to 1-2 mL. A second
eqivalent of the phosphine was then added. Very large block crystals
of the product grew from the solution overnight at -20 °C. The overall
yield was 0.96 g (20%).
Synthesis of Zn(O-2,6-Ph2C6H3)2(Ph2PMe) (9). 2,6-Diphenylphenol
(0.12 g, 1 mmol) in 5 mL of toluene was added to Zn[N(SiMe3)2]2
(0.195 g, 0.5 mmol) dissolved in 3 mL of toluene. The mixture was
stirred for 30 min followed by addition of Ph3PMe. After the mixture
was stirred for an additional 30 min, the volatiles were pulled away in
vacuo, leaving behind a tacky, foamy solid. The material was stirred
in cold hexane and filtered, giving 0.28 g (73%) of the white powdery
product. 1H NMR (CD2Cl2): δ 3.24 (d, 3H), 6.4-7.4 (m, 36H, phenyl).
13C NMR (CD2Cl2): δ 55.2(PCH3), 115.3, 121.1, 126, 128.2, 128.5,
128.9, 129.1, 129.3, 132.1, 138, 141.9. 31P NMR (CD2Cl2): δ 0.29.
Synthesis of Zn(O-2,6-Ph2C6H3)2(PCy3) (10). Preparation and
isolation were very similar to that for 9. Removal of the toluene in
vacuo left a colorless oil. Pentane was added to the oil, and after the
mixture was stirred for several minutes, the product was isolated as a
white powder in 48% yield. 1H NMR (C6D6): δ 0.8-1.6 (b, 33H,
PC6H11), 6.58 (t, 2H, p-C6H5), 6.85-7.5 (b, 22H, Ph). 13C NMR
(C6D6): δ 26.1, 27.3 (d), 29.3, 30.5 (d), 116, 123.2, 142, 160.5 (ipso).
31P NMR (C6D6): δ 12.2.
1
to H3PO4 (85% in D2O). H and 13C NMR spectra were acquired on
Varian XL200E, Unity+ 300 MHz, and VXR 300 MHz superconduct-
ing NMR spectrometers. The operating frequencies for 13C experiments
were 50.29 and 75.41 MHz for the 200 and 300 MHz instruments,
respectively. Infrared spectra were recorded on a Mattson 6021 FT-IR
spectrometer with DTGS and MCT detectors.
Synthesis of Zn(O-2,6-tBu2C6H3)2(PPh2Me) (1). To Zn[N(SiMe3)2]2
(0.195 g, 0.5 mmol) in 5 mL of toluene was added a 5 mL toluene
solution of 2,6-di-tert-butylphenol (0.206 g, 1 mmol). The mixture was
stirred for 15 min followed by the addition of PPh2Me (0.10 g, 0.5
mmol) via a syringe. Stirring of the reaction solution was continued
for an additional 30 min, and then the solution was concentrated in
vacuo to approximately 2-3 mL. Crystals were obtained through slow
diffusion of hexane into the toluene reaction at -20 °C over several
days. The yield after drying was 0.16 g (48%). Anal. Calcd for
1
ZnC41H55O2P: C, 71.1; H, 8.15. Found: C, 72.85; H, 8.14. H NMR
(CD2Cl2): δ 1.25 (d, JP-H ) 6.8 Hz, 3H, PCH3), 1.61 (s, 18H, C(CH3)3),
6.8-7.2 (m, 16H, Ph), 7.38 (d, 2H, p-C6H3). 13C NMR (CD2Cl2):
δ 31.92 (C(CH3)3), 35.93 (PCH3) 165.64 (ipso-C6H3). 31P NMR
(CD2Cl2): δ -19.9.
Syntheses of the other monophosphine derivatives of Zn(O-2,6-
tBu2C6H3)2 were accomplished in an manner analogous to that described
for complex 1.
(15) Goel, R. G.; Henry, W. P.; Jha, N. K. Inorg. Chem. 1982, 21, 2551.
(16) Goel, R. G.; Ogiini, W. O. Inorg. Chem. 1977, 16, 1968.
(17) Bochmann, M.; Bwembya, G. C.; Grinter, R.; Powell, A. K.; Webb,
K.; Hursthouse, M. B.; Abdul-Malik, K. M.; Magid, M. A. Inorg.
Chem. 1994, 33, 2290.
(18) Zeng, D.; Hampden-Smith, M. J.; Alam, T. M.; Rheingold, A. L.
Polyhedron 1994, 13, 2715.
(19) McAuliffe, C. A.; Bricklebank, N.; Godfrey, S. M.; Mackie, A. G.;
Pritchard, R. G. J. Chem. Soc., Chem. Commun. 1992, 944.
(20) Darensbourg, D. J.; Zimmer, M. S.; Rainey, P.; Larkins, D. L. Inorg.
Chem. 1998, 37, 2852.
Synthesis of Zn(O-2,6-Ph2C6H3)2(PMe3) (11). Complex 11 was
made in a fashion analogous to that of 9 and isolated as a solid in 57%
1
yield. H NMR (C6D6): δ -0.49 (d, 9H, JP-H ) 14.1), 6-7.35 (m,
14H), 7.812 (d, 4H, m-C6H3). 31P NMR (C6D6): δ -47.4.
Synthesis of Zn(O-2,6-Ph2C6H3)2(PEt3) (12). The synthesis was
1
similar to that for 9 and isolated in 32% yield. H NMR (C6D6): δ
0.42 (m, 3H, PCH2CH3), 0.63 (m, 2H, PCH2CH3), 6.87 (t, 2H), 7.39
(d, 4H, o-C6H5), 7.86 (d, 4H, m-C6H3). 31P NMR (C6D6): δ -12.1 (b).