Hofmann et al.
were distilled over Na and kept under Ar. Benzene-d6 and toluene-
d8, dichloromethane-d2 were stirred over CaH2 and degassed trice
prior to use. THF-d8 was refluxed over Na and degassed trice.
Styrene was distilled in vacuum, degassed trice and kept under Ar
in the glovebox at -15 °C.
18H); 13C{1H} NMR (248 K, toluene-d8, 125.77 MHz): δ 239.7
(s, Cu)C), 160.0, 147.3, 128.5, 125.2 (all s, arom. C), 37.3 (d,
2
1JCP 63.2 Hz, C(CH3)3), 27.2 (d, JCP 2.4 Hz, C(CH3)3), 5.2 (s,
Si(CH3)3); 31P{1H} NMR (248K, toluene-d8, 202.47 MHz): δ 66.7
1
2
(s+sat, JPC 62.6 Hz, JPSi 11.8 Hz). Anal. Calc. for
C27H44CuN4O4PSi2 (%): C 50.72; H 6.94; N 8.76; P 4.84. Found:
C 50.97, H 7.01, N 8.75, P 4.60. FAB (NPOE): m/z ) 639.3 (2.2%)
[MH+], 581.1 (6.5%) [(M+) - tBu)], correct isotopic pattern. A
sample of 4b suitable for X-ray analysis was obtained by slow
crystallization from a diluted hexane solution at -35 °C over a
period of 1 month.
Diphenyldiazomethane,18 di(p-tolyl)diazomethane,18 di(p-nitro-
phenyl)diazomethane,19 were synthesized according to known
procedures. NMR spectra were recorded on a Bruker 250 or 500
1
MHz spectrometer at temperatures specified below. H,13C NMR
chemical shifts are reported in parts per million and are referenced
to the deuterated solvent used.
[But2P(NSiMe3)2-K2N]CudC(p-MeC6H4)2 (4c). A solution of
di(p-tolyl)diazomethane (24.3 mg, 0.109 mmol) in toluene-d8 (0.3
mL) was added to a solution of the copper complex 3 (50 mg,
0.122 mmol) in toluene-d8 (0.3 mL), and a deep-violet solution
was formed. The reaction mixture was agitated at r. t. for 4 min
and placed in an NMR tube. The copper carbene 4c in a 27%
Calculations were carried out on a 56 CPU cluster with Intel
Xeon processors (2.66 GHz) using Turbomole (version 5.7)20
software package. For the DFT calculations, the BP86 functional
(Becke’s exchange21 and Perdew’s gradient corrected22 correlation
functional) was utilized. The implemented split-valence SV(P) basis
set was employed for geometry optimization of 4b, whereas a
triple-ꢁ quality basis TZVP was used for the single-point energy
calculation on the SV(P)-optimized structure of 4b.
1
steady-state concentration was detected by H, 31P and 13C NMR
1
spectroscopy. H NMR (253K, toluene-d8; 500.13 MHz): δ 8.26
[But2P(NSiMe3)2-K2N]Cu)CPh2 (4a). To a solution of 3 (60
mg, 0.146 mmol) in toluene-d8 (0.3 mL) in an NMR tube was added
a solution of diphenyldiazomethane (31 mg, 0.16 mmol)) in toluene-
d8 (0.3 mL). The reaction mixture instantly became intensively
violet and gas evolution was observed. Spectral data of 4a: 1H NMR
(248 K, toluene-d8; 500.13 MHz): δ 8.28 (d, 3JHH 7.3 Hz, o-arom.
H; 4H), 7.39 (t, 3JHH 7.6 Hz, p-arom. H; 2H), 1.46 (d, 3JPH 14 Hz,
C(CH3)3; 18H), 0.31 (s, Si(CH3)3; 18H); 13C{1H} NMR (248 K,
(d, 3JHH ) 8.3 Hz, 4 arom. H), 6.94 (d, 3JHH ) 8.3 Hz, 4 arom. H),
3
1.88 (s, 6H, CH3), 1.51 (d, JHP ) 13.7 Hz, 18H, C(CH3)3), 0.35
(s, 18H, Si(CH3)3). 31P{1H} NMR (253K, toluene-d8, 202.47 MHz):
1
2
δ 57.9 (s+sat, JPC ) 64.5 Hz, JPSi ) 16.1 Hz). 13C{1H} NMR
(253K, toluene-d8, 125.77 MHz): δ 266.4 (s, Cu)C), 37.2 (d, 1JPC
) 64.3 Hz, C(CH3)3), 27.8 (s, C(CH3)3), 22.1 (s, CH3), 5.39 (s,
Si(CH3)3).
{[But2P(NSiMe3)2-K2N]Cu}2(µ-CPh2) (5). To a stirred solution
of 3 (100 mg, 0.243 mmol) in hexane (2.5 mL) was added a solution
of diphenyldiazomethane (35 mg, 0.182 mmol) in hexane (2.5 mL).
The resulting, intensely violet solution was stirred for 50 min at
ambient temperature and then slowly concentrated at 10-3 mbar to
give a dark crystalline residue. Hexane (8 mL) was added, and the
reaction mixture was stirred for 15 min at room temperature, then
filtered under Ar via a cannula into a cooled to 0 °C Schlenk vessel.
The brown solution was slowly cooled to -80 °C and kept at this
temperature overnight. The solvent above the precipitated dark
crystals (some of which were suitable for X-ray analysis) was
removed via cannula, and the product was washed two times with
cold (-78 °C) hexane and dried in high vacuum (10-3 mbar) to
yield complex 5 (53 mg). The compound decomposes in solution
at room temperature, and the isolated solid is contaminated with
carbene 4a. Spectral data of 5: 1H NMR (263 K, toluene-d8; 500.13
MHz): δ 1.41(br. s, C(CH3)3; 9H), 1.05 (br. s, C(CH3)3; 9H), 0.88
(br. s, Si(CH3)3; 9H); 0.26 (br. s, Si(CH3)3; 9H); 13C{1H} NMR
(263 K, toluene-d8, 125.77 MHz): δ 184.7 (Cu-µ-CPh2), 38.0-39.0
(br. m, 2C(CH3)3), 29.4 (br. s, C(CH3)3), 28.5 (br. s, C(CH3)3); 9.1
(br. s, Si(CH3)3); 7.1 (br. s, Si(CH3)3); 31P{1H} NMR (263K,
1
toluene-d8, 125.77 MHz): δ 264.5 (s, Cu)C), 37.2 (d, JCP 64.4
2
Hz, C(CH3)3), 27.7 (d, JCP 2.4 Hz, C(CH3)3), 5.3 (s, Si(CH3)3);
31P{1H} NMR (248 K, toluene-d8, 202.47 MHz): δ 59.6 (s+sat,
1JPC 63.9 Hz, 2JPSi 14.8 Hz); the signals for m-arom. protons overlap
with signals of the diazoalkane. Compound 4a cannot be isolated
completely free of starting material 3.
[But2P(NSiMe3)2-K2N]CudC(p-NO2C6H4)2 (4b). A mixture of
3 (200 mg, 0.487 mmol) and di(p-nitrophenyl)diazomethane (131
mg, 0.462 mmol) was stirred in absolute toluene (14 mL) at 55 °C
for 35 min. The dark-violet solution was evaporated at 0 °C and
10-3 mbar. The residue was treated with absolute hexane (12 mL),
vigorously stirred at r.t. for 5 min, and the solution obtained was
filtered under Ar via cannula into a Schlenk vessel cooled to 0 °C.
The violet solution was slowly cooled to -80 °C and kept at this
temperature overnight. A dark crystalline solid deposited. The
solvent was removed from the crystals via cannula, and the product
was washed with cold (-78 °C) hexane (2 × 2 mL). The reaction
vessel was then evacuated to 10-3 mbar, and the temperature was
slowly increased to -10 °C. Finally, the product was dried in vacuo
(10-3 mbar) for 4 min at 20 °C to completely remove the solvent.
Yield based on diazo compound 55%. The product slowly
decomposes in solution and in the solid state at room temperature,
but at lower temperatures it can be kept under Ar even in solution
without significant decomposition. 1H NMR (248K, toluene-d8;
1
2
toluene-d8, 202.47 MHz): δ 65.4 (s+sat, JPC 60.9 Hz, JPSi 11.7
Hz).
Reaction of 4b with (p-CH3C6H4)2CdN2. A solution of carbene
4b (10 mg, 0.0157 mmol) in THF-d8 (0.3 mL) at r. t. was added to
a solution of an excess of (p-CH3C6H4)2CdN2 (14 mg, 0.0631
mmol) in THF-d8 (0.3 mL), and gas evolution was observed. All
4b was consumed within several minutes. Spectroscopic data for
3
500.13 MHz): δ 7.91 (d, JHH 8.5 Hz, o-arom. H; 4H), 7.71 (d,
1
3
3JHH 8.5 Hz, m-arom. H; 4H), 1.36 (d+sat, JCH 124.8 Hz, JPH
1
14.3 Hz, C(CH3)3; 18H), 0.19 (s+sat, JCH 117.5 Hz, Si(CH3)3;
1
3
the mixed azine 9: H NMR (500 MHz, THF-d8): δ 8.34 (d, JHH
(18) Mussons, M. L.; Raposo, C.; Anaya, J.; Grande, M.; Mora´n, J. R.;
Caballero, M. C. J. Chem. Soc. Perkin Trans. 1 1992, 3125.
(19) Just, G.; Wang, Z. Y.; Chan, L. J. Org. Chem. 1988, 53, 1030.
(20) (a) Eichkorn, K.; Treutler, O.; Oehm, H.; Haeser, M.; Ahlrichs, R.
Chem. Phys. Lett. 1995, 240, 283. (b) Eichkorn, K.; Treutler, O.;
Oehm, H.; Haeser, M.; Ahlrichs, R. Chem. Phys. Lett. 1995, 242, 652.
(c) Ahlrichs, R.; Baer, M.; Haeser, M.; Horn, H.; Koelmel, C. Chem.
Phys. Lett. 1989, 162, 165.
3
) 8.35 Hz, 4H arom.), 8.17 (d, JHH ) 8.65 Hz, 4H arom.), 7.70
(d, 3JHH ) 8.65 Hz, 4H arom.), 7.61 (d, 3JHH ) 8.35 Hz, 4H arom.),
2.39 (s, 3H, 2CH3). MS-EI+: m/z ) 478.1 (40%) (M+). Spectro-
1
scopic data for the mixed dimer 10: δ H NMR (500 MHz, THF-
d8): 8.39 (d, 3JHH ) 8.35 Hz, 4H arom.), 8.03 (d, 3JHH ) 8.05 Hz,
3
3
4H arom.), 7.66 (d, JHH ) 8.0 Hz, 4H arom.), 7.29 (d, JHH
)
(21) Becke, A. D. Phys. ReV. 1988, A38, 3098.
(22) (a) Perdew, J. P.; Zunger, A. Phys. ReV. 1981, B23, 5048. (b) Perdew,
J. P. Phys. ReV. 1986, B33, 8822.
8.35 Hz, 4H arom.), 2.41 (s, 6H, 2CH3). MS-EI+: m/z ) 450.1
(20%) (M+).
11760 Inorganic Chemistry, Vol. 47, No. 24, 2008