6620 J . Org. Chem., Vol. 64, No. 18, 1999
Kashimura et al.
cooling by ice-water bath. During the electroreduction the
polarity of the electrodes was alternated with an interval of
15 s using a comutator. The substrate chlorosilane (6 mmol)
was then syringed into the cell in a stream of nitrogen, and
the solution was further electrolyzed. The progress of the
reaction was monitored by GLC or TLC. After the starting
material was consumed (supplied electricity ) ca. 2 F/mol
based on the substrate chlorosilane), the reaction mixture was
poured into ice cold 1 N HCl (100 mL), and the aqueous
solution was extracted with ether (50 mL × 3). The combined
organic layer was washed twice with 50 mL of brine, dried
over MgSO4, and concentrated. The residue was purified by a
silica gel column, eluting with hexane.
Sch em e 15
applied to the reaction system. The molecular weight and
yield of the polymers was controlled by the concentration
of monomer and the amount of supplied electricity.
Because the present electroreductive polymerization
requires only a single compartment cell and moderate
conditions, it is undoubtedly one of the simplest and most
powerful tools for synthesis of polysilane, polygermane
and related polymers.
1,2-Diph en yltetr am eth yldisilan e (2a):22,38 IR (neat) 3050,
2960, 1430, 1250, 1110 cm-1; 1H NMR (CDCl3) δ 0.35 (s, 12H),
7.20-7.65 (m, 10H); 13C NMR (CDCl3) δ -3.82, 127.71, 128.41,
133.88, 138.98; MS m/z (relative intensity) 270 (5, M+), 255
(30, M+ - Me), 193 (62, M+ - Ph), 135 (100, PhMe2Si+).
Hexa m eth yld isila n e (2b):39 IR (neat) 2950, 2890, 1250
cm-1 1H NMR (CDCl3) δ 0.02 (s, 6H); 13C NMR (CDCl3) δ
;
-2.71; MS m/z (relative intensity) 146 (13, M+), 131 (18, M+
- Me), 73 (100, Me3Si+).
Exp er im en ta l Section
1,2-Dim eth yltetr a p h en yld isila n e (2c):22,38 IR (KBr) 3020,
1420, 1250, 1100 cm-1; 1H NMR (CDCl3) δ 0.69 (s, 6H), 7.15-
7.65 (m, 20H); 13C NMR (CDCl3) δ -4.25, 128.06, 129.16,
135.47, 136.84; MS m/z (relative intensity) 394 (1, M+), 197
(100, Ph2MeSi+).
Gen er a l. 1H and 13C NMR spectra were obtained at 200
and 50 MHz and were recorded in CDCl3. Mass spectra were
obtained in the electron-impact (EI) mode. Elemental analyses
were performed by the Center for Instrumental Analysis of
Kyoto University. Molecular weights of polymers and oligo-
mers were determined by gel permeation chromatography
(GPC) using THF as an eluent, relative to polystyrene stand-
ards. The constant electrocurrent was supplied with Takasago
GPO 50-2 regulated DC power supply. The supplied electricity
was counted by a Hokuto Denko Coulomb amperehour meter
HF-201. The sonication by ultrasound (47 kHz) was performed
by using a Yamato Branson 2200.
Hexa p h en yld isila n e (2d ):39 IR (KBr) 3040, 1420, 1100
cm-1; 1H NMR (CDCl3) δ 7.20-7.70 (m, 30H); 13C NMR (CDCl3)
δ 128.15, 130.38, 135.25, 136.75; MS m/z (relative intensity)
518 (2, M+), 259 (100, Ph3Si+).
Cr oss Cou p lin g of Ch lor otr im eth ylsila n e (1b) a n d
Ch lor otr ip h en ylsila n e (1d ). A solution of chlorotrimethyl-
silane (1b) (3 mmol) and chlorotriphenylsilane (1d ) (3 mmol)
in 15 mL of dry THF was electrolyzed by using the same
procedure described above (supplied electricity ) 580 C) to give
2d (GLC yield, 25%) and 1,1,1-trimethyl-2,2,2-triphenyldi-
silane (2e) (GLC yield, 25%). 2e:40 1H NMR (CDCl3) δ 0.20 (s,
9H), 7.30-7.50 (m, 15H); 13C NMR (CDCl3) δ -1.04, 127.95,
128.17, 129.22, 136.17.
Ma t er ia l. Organomonochlorosilanes 1a -e and organo-
dichlorosilanes 3a ,b are commercially available from Shin-
Etsu Chemical Co. Ltd., and they were used after distillation.
Dichlorodimesitylsilane (3c),35 1,2-dichloro-1,1,2-trimethyl-2-
phenyldisilane (5),36 1,4-bis(chloroethylmethylsilyl)benzene
(17a ),37 and 1,4-bis(chloromethylphenylsilyl)benzene (17b)38
were prepared by reported methods. Dichloro-4-(2-oxapropoxy)-
phenylphenylsilane (3d ) was prepared by the reaction of a
Grignard reagent from 4-bromophenol methoxymethyl ether
with phenyltrichlorosilane. Tetrachlorogermane was obtained
from Aldrich and used after distillation. Dichlorobutylphenyl-
germane (13) was prepared by a reported method.31 Tetrahy-
drofuran (THF) was distilled from Na-benzophenoneketyl
Tr isila n e. A solution of chlorosilane 1 (15 mmol) and
dichlorosilane 3 (3 mmol) in dry THF was electrolyzed by using
the same procedure for the preparation of disilane to afford
trisilane (supplied electricity ) ca. 4F/mol based on 3).
2-P h en ylh ep ta m eth yltr isila n e (4a ):22,41 IR (neat) 3050,
1
2940, 2890, 1425, 1245, 1095 cm-1; H NMR (CDCl3) δ 0.11
(s, 18H), 0.37 (s, 3H), 7.25-7.34 (m, 3H), 7.36-7.42 (s, 2H).
2,2-Dip h en ylh exa m eth yltr isila n e (4b):41 IR (neat) 2950,
2875, 1430, 1250, 1100 cm-1; 1H NMR (CDCl3) δ 0.15 (s, 18H),
7.26-7.37 (m, 6H), 7.40-7.50 (m, 4H); MS m/z (relative
under
a nitrogen atmosphere. Magnesium ingot is com-
mercially available from Rare Metallic Co. Ltd. and was cut
into rods (Φ ) 9 mm, length ) 4 cm) for electrodes. The
electrodes were treated with concentrated HCl and then
washed with water and acetone.
intensity) 328 (28, M+), 255 (67, M+ - SiMe3), 178 (100, M+
-
SiMe3 - Ph); HRMS calcd for C18H28Si3 328.1499, found
328.1493.
2,2-Dim esitylh exa m eth yltr isila n e (4c):42 IR (KBr) 2950,
1440, 1240 1100 cm-1; 1H NMR (C6D6) δ 0.25 (s, 18H), 2.12 (s,
6H), 2.29 (broad s, 12H), 6.75 (s, 4H); MS m/z (relative
Disila n e. The electrolysis of organomonochlorosilanes was
carried out in a 30-mL three-necked flask equipped with Mg
cathode and anode and a three-way stopcock jointed to a
balloon of nitrogen. Into this cell was placed 0.7 g of LiClO4,
and the content of the cell was dried at 50 °C in vacuo for 3 h.
Chlorotrimethylsilane (0.1 mL) and 15 mL of dry THF were
then added under a nitrogen atmosphere. After the solution
was magnetically stirred for 3 h, the pre-electrolysis was
carried out to remove traces of water and residual chlorotri-
methylsilane from the electrolysis system; that is, 600 C of
electricity was passed through the cell under a constant
current condition (current density ) 30 mA/cm2) with external
intensity) 412 (10, M+), 397 (4, M+ - Me), 339 (100, M+
-
SiMe3); HRMS calcd for C24H40Si3 412.24377, found 412.24542.
2-P h en yl-2-[4-(2-oxa p r op oxy)p h en yl]h exa m et h ylt r i-
1
sila n e (4d ): IR (KBr) 2950, 2900, 1500, 1240, 1100 cm-1; H
NMR (CDCl3) δ 0.18 (s, 18H), 3.51 (s, 3H), 5.21 (s, 2H), 6.95-
7.05 (m, 2H), 7.25-7.50 (m, 7H).
2-P h en yln on a m eth yltetr a sila n e (6).43 A solution of chlo-
rotrimethylsilane (1b ) (15 mmol) and 1,2-dichloro-1,1,2-tri-
methyl-2-phenyldisilane (5) in dry THF was electrolyzed by
(34) Kunai, A.; Toyoda, E.; Kawakami, T.; Ishikawa, M. Organo-
metallics 1992, 11, 2899.
(35) Fink, M. J .; Michalczyk, M. J .; Haller, K. J .; West, R. Organo-
metallics 1984, 3, 793.
(39) The structures of 2b and 2d are confirmed by comparison with
the spectroscopic data of the commercially available authentic samples.
(40) Hiyama, T.; Obayashi, M.; Mori, I.; Nozaki, H. J . Org. Chem.
1983, 48, 912.
(36) Wolff, A. R.; Nozue, I.; Maxka, J .; West, R. J . Polym. Sci., Part
A: Polym. Chem. 1988, 26, 701.
(37) Nate, K.; Ishikawa, M.; Ni, H.; Watanabe, H.; Saheki, Y.
Organometallics 1987, 6, 1673.
(41) Bobbitt, K. L.; Gaspar, P. P. J . Organomet. Chem. 1995, 449,
17.
(42) Fink, M. J .; Michalczyk, M. J .; Haller, K. J .; West, R.; Michl,
J . Oraganometallics 1984, 3, 793.
(38) Gilman, H.; Lichtenwalter, G. D.; Wittenberg, D. J . Am. Chem.
Soc. 1959, 81, 5320.
(43) Semenov, V. V.; Cherepennikova, N. F.; Arthemicheva, S. B.;
Razuvaev, G. A. Appl. Organomet. Chem. 1990, 4, 163.