Note
Organometallics, Vol. 29, No. 13, 2010 3057
Scheme 4. Proposed Mechanism for the Formation of Compound 4
reflections collected in the θ range of 3.33ꢀ to -27.46ꢀ, using ω
scans on a Rigaku R-axis Rapid S diffractometer, 2047 were
unique reflections (Rint = 0.026, completeness = 98.8%). The
structure was solved and refined against F2 using SHELX97,11
trichloro(2-(dichloro(methyl)silyl)ethyl)silane (5) (1.4 g, 20%),
at 90 ꢀC/10 mmHg to give bissilylation products (6) (3.4 g, 38%),
and at 160 ꢀC/10 mmHg to give 1,1,4,4-tetrachloro-2,5-bis-
(methyldichlorosilyl)-1,4-disilacyclohexane (4) as colorless liquids.
Compound 4 was dissolved in hexane and then recrystallized at
0 ꢀC to give 4 (2.5 g, 42%). Repeated recrystallization from hexane
allowed the isolation of the pure trans isomer as the first crop. Data
2
94 variables, wR2=0.1103, R1=0.0394 (Fo2 > 2σ(Fo )), GOF =
1.163, and a max./min. residual electron density of 1.321/-
0.683 e A-3. Crystal structure data for compound 4: triclinic, space
˚
1
˚
˚
˚
group P1, a = 6.7991(3) A, b = 8.6802(4) A, c = 9.2531(5) A,
R = 84.181(2)ꢀ, β = 67.190(2)ꢀ, γ = 71.425(1)ꢀ, V = 477.01(4)
for 4: initial cis-trans isomer mixture: mp 86-90 ꢀC; H NMR
(CDCl3) δ 1.82-1.75 (t, 4H, Si-CH2-C), 1.56-1.50 (m, 4H, Si-
CH2-C), 1.41-1.37, 1.29-1.71; 13C NMR δ 20.7, 18.2, 16.7, 14.2,
6.5, 6.2, 5.7; 29Si NMR δ 27.3, 25.2, 21.1, 18.0; pure trans isomer:
mp 92-94 ꢀC; 1H NMR (CDCl3) δ 1.84, 1.57, 1.43, 0.97 (s, 6H,
Si-CH3); 13C NMR δ 20.7, 16.7, 6.45; 29Si NMR δ 25.2, 18.0.
Data for 5: 1H NMR (CDCl3) δ 1.50 (t, 2H, CH3Cl2Si-CH2-C),
1.27 (t, 2H, Cl3Si-CH2-C), 0.82 (s, 3H, CH3Cl2Si-CH2); 13C NMR
δ 16.5, 13.8, 4.8.
3
˚
A , Z=1, T = 150(2) K, crystal dimension 0.40 ꢀ 0.20 ꢀ 0.15
mm3, Mo KR = 1.775 mm-1. Of 4602 reflections collected in the
θ range of 3.35ꢀ to -27.48ꢀ, using ω scans on a Rigaku R-axis
Rapid S diffractometer, 2137 were unique reflections (Rint = 0.016,
completeness = 98.0%). The structure was solved and refined
against F2 using SHELX97,11 82 variables, wR2 = 0.0838, R1 =
0.0272 (Fo2 > 2σ(Fo )), GOF = 1.220, and a max./min. residual
2
-3
˚
General Procedure for 2,5-Bissilyl-1,4-disilacyclohexane (10)
and 2,5-Bis(methylsilyl)-1,4-disilacyclohexane (40). Lithium alu-
minum hydride (1.0 g, 26.6 mmol) and dry diethyl ether (20 mL)
were added to a 100 mL three-necked flask equipped with a
magnetic stir bar, rubber septum, and vacuum adapter. The
flask was cooled to 0 ꢀC with constant stirring, and the corre-
sponding chlorosilane (10 mmol) in diethyl ether (10 mL) was
added dropwise through a dropping funnel. After the addition,
the mixture was warmed to room temperature for 1 h and stirred
at room temperature for 3 h. The remaining LiAlH4 was
quenched with a 5% acetic acid aqueous solution at 0 ꢀC, and
the organic layer was separated and dried over MgSO4. After
filtration, the products were distilled at 760 mmHg to give
compounds 10 and 40. Data for 2,5-bissilyl-1,4-disilacyclohexane
(10): yield 82%; bp 142 ꢀC; 1H NMR (CDCl3) δ 3.92-3.83 (m,
4H, CH-SiH2-CH2), 3.67-3.62 (m, 6H, CH-SiH3), 1.26-0.87
electron density of 0.502/-0.498 e A
.
Reaction of Trichlorosilane with Vinyltrichlorosilane in the
Presence of [Bu4P]þCl-. Vinyltrichlorosilane (3.0 g, 19 mmol),
trichlorosilane (7.5 g, 57 mmol), and [Bu4P]þCl- (0.6 g, 2 mmol)
were added to a 25 mL stainless steel tube under a dry nitrogen
atmosphere. The tube was sealed with a cap, and the reaction
mixture was heated at 150 ꢀC for 3 h. After cooling, the reaction
mixture was transferred to a 25 mL one-necked flask with a
double-tipped needle. The mixture consisted of two layers of an
organic phase and a catalyst. The reaction mixture was sepa-
rated from the catalyst by filtration. The filtrates were separated
by bulb-to-bulb vacuum distillation at 82 ꢀC/10 mmHg to give
1,2-bis(trichlorosilyl)ethane (2) (1.5 g, 27%), at 98 ꢀC/10 mmHg
to give 1,1,2-tris(trichlorosilyl)ethane (3) (2.3 g, 28%), and at
175 ꢀC/mmHg to give 1,1,4,4-tetrachloro-2,5-bis(trichlorosilyl)-
1,4-disilacyclohexane (1) as colorless liquids. Compound 1 was
dissolved in hexane and then recrystallized at 0 ꢀC to give 1 (2.2 g,
44%). Repeated recrystallization from hexane allowed the isola-
tion of the pure trans isomer as the first crop. Data for 1: initial
cis-trans isomer mixture: mp 106-110 ꢀC; 1H NMR (CDCl3) δ
1.80-1.85 (t, 2H, Si-CH2-Si), 1.57-1.70 (d, 4H, Si-CH2-C); 13C
NMR δ 23.0, 20.8, 17.0, 14.5; 29Si NMR δ 21.3, 18.2, 6.2, 5.5; pure
trans isomer: mp 111-113 ꢀC; 1H NMR (CDCl3) δ 1.84-1.88 (t, 2H,
Si-CH2-Si), 1.64-1.75 (d, 4H, Si-CH2-C); 13C NMR δ 23.0, 17.0;
29Si NMR δ 18.2, 5.5. Data for 2: 1H NMR (CDCl3) δ 1.58 (s, 2H,
Si-CH2-C); 13C NMR δ 16.5. Data for 3: 1H NMR (CDCl3) δ 1.94-
1.98 (t, 1H, Si-CH-Si), 2.05 (d, 2H, Si-CH2-C); 13CNMRδ24. 5, 18.5.
Reaction of Dichloromethylsilane with Vinyltrichlorosilane in
the Presence of [Bu4P]þCl-. A procedure analogous to that
described above was used. Vinyltrichlorosilane (4.0 g, 25 mmol),
dichloromethylsilane (8.6 g, 75 mmol), and [Bu4P]þCl- (0.7 g,
2.5 mmol) were added to a 25 mL stainless steel tube, and the
reaction mixture was heated to 180 ꢀC for 6 h. After cooling, the
reaction mixture was transferred to a 25 mL one-necked flask
with a double-tipped needle. The reaction mixture was sepa-
rated from the catalyst by filtration. The filtrates were separated
by bulb-to-bulb vacuum distillation at 75 ꢀC/10 mmHg to give
(m, 4H, SiH2-CH2-CH), 0.43-0.49 (m, 2H, SiH2-CH-SiH3); 13
C
NMR (CDCl3) δ -3.8 (SiH2-CH2-CH), -6.4 (CH2-CH-SiH3).
Anal. Calcd for C4H16Si4 (176.51): C 27.22, H 9.14. Found: C
27.21, H 9.16. Data for 2,5-bis(methylsilyl)-1,4-disilacyclohex-
ane (40): yield 90%; bp 166 ꢀC; 1H NMR (CDCl3) δ 3.77 (q, 4H,
CH2-SiH2-CH), 3.61-3.68 (m, 4H, CH-SiH2-CH3), 1.20-0.83
(tm, 4H, SiH2-CH2-CH), 0.34-0.47 (m, 2H, SiH2-CH-SiH2),
0.18 (t, 6H, CH-SiH2-CH3); 13C NMR (CDCl3) δ 8.0 (Si-CH2-
CH), 0.3 (Si-CH-Si), -8.9 (Si-CH3). Anal. Calcd for C6H20Si4
(204.57): C 35.23, H 9.85. Found: C 35.13, H 9.87.
Acknowledgment. This study was supported by the
National Research Foundation of Korea (NRF) grant
funded by the Korean government (MEST) (No. 2010-
0018456) and the Center for Fuel Cell Research of the
Korea Institute of Science and Technology.
Supporting Information Available: X-ray diffraction data for
compounds 1 and 4. 1H and 13C spectra for all compounds and 29Si
NMR for 1 and 4. GC data for the reaction of dichloromethylsilane
with vinyltrichlorosilane in the presence of [Bu4P]þCl-.Thismaterial
(11) Sheldrick, G. M. Acta Crystallogr. 2008, A64, 112.