Phosphine-Catalyzed Si-C Coupling of Bissilylmethanes: Preparation of Cyclic (Cl2SiCH2)2 and Linear Cl 2Si(CH2SiCl3)2 via Silylene and Silene Intermediates

Article abstract of DOI:10.1021/om901071k

Cyclic and linear carbosilanes, (Cl₂SiCH₂) ₂ (2) and Cl₂Si(CH₂SiCl₃) ₂ (3), were produced from phosphine-catalized Si-C coupling reactions of bissilylmethanes, HCl₂SiCH₂SiX₁X ₂Cl (X₁, X₂ = Cl (1), X₁ = H, X ₂ = Cl (7), and X₁ = Me, X₂ = Cl (8)). The formation of compounds 2 and 3 suggested competing reaction pathways, involving dichlorosilene [CH₂=SiCl₂] and dichlorosilylene [:SiCl₂] intermediates. Each intermediate was either proposed by the product isolation of the trimerized product (3) or confirmed by trapping experiments with 2,3-dimethylbutadiene and methylene chloride.

Full text of DOI:10.1021/om901071k

Organometallics 2010, 29, 687–691 687
DOI: 10.1021/om901071k
Phosphine-Catalyzed Si-C Coupling of Bissilylmethanes: Preparation
of Cyclic (Cl SiCH ) and Linear Cl Si(CH SiCl ) via Silylene
and Silene Intermediates
2
2 2
2
2
3 2
†
,‡
†,‡
Soon Hyun Hong, Sang Il Hyun, Il Nam Jung,* Won-Sik Han, Min-Hye Kim,
,†,‡
†
†
§
Hoseop Yun, Suk-Woo Nam, and Sang Ook Kang*
^
,†
†
Department of Chemistry, Korea University, 208 Seochang, Chochiwon, Chung-nam 339-700, South Korea,
JSI Silicone Co., Rm#1511, Megacenter, SK Technopark, Jungwon, Seongnam 462-807, South Korea,
Department of Chemistry, Ajou University, Suwon 443-749, South Korea, and Center for Fuel Cell
Research, Korea Institute of Science and Technology, 39-1 Hawolgok-dong, Sungbuk-gu,
Seoul 136-791, South Korea
‡
§
^
Received December 16, 2009
Cyclic and linear carbosilanes, (Cl SiCH ) (2) and Cl Si(CH SiCl ) (3), were produced from
3 2
2
2 2
2
2
phosphine-catalized Si-C coupling reactions of bissilylmethanes, HCl SiCH SiX X Cl (X , X =
2
2
1
2
1
2
Cl (1), X =H, X =Cl (7), and X =Me, X =Cl (8)). The formation of compounds 2 and 3 sug-
gested competing reaction pathways, involving dichlorosilene [CH dSiCl ] and dichlorosilylene
1
2
1
2
2
2
[:SiCl ] intermediates. Each intermediate was either proposed by the product isolation of the
2
trimerized product (3) or confirmed by trapping experiments with 2,3-dimethylbutadiene and
methylene chloride.
Introduction
organosilanes with the formula (SiCl CH ) (x g 3) and
2 2 x
X Si(CH ) SiX Y (X = Cl, Y = H or Cl, n = 1-4) were
3
2 n
2
Carbosilanes have attracted considerable interest for their
produced using this process. However, there was no detailed
information regarding the identification of each compound.
1
potential applications in ceramic, optical, conducting, and
2
3
4
electronic materials. The direct reactions of elemental sili-
7
Later, Fritz, and Matern examined the same reaction using
con and alkyl chlorides were reported to be the most effective
for the preparation of carbosilane compounds, and opti-
a fluidized-bed reactor at 320 ꢀC and isolated more than
40 carbosilanes ranging from one to 12 silicon atoms, including
5
mized protocols are now available in the literature. In 1945,
Patnode and Schiessler reported the first direct reaction of
8
six- and eight-membered cyclic carbosilanes, (Cl SiCH )
2
2 3
9
and (Cl SiCH ) . Although the reactions were carried out
2 2 4
6
silicon with CH Cl over a copper catalyst. Cyclic and linear
2
2
on a large scale using a continuous process, the yields of
distillable products were only ∼20%, partly due to the
decomposition of methylene chloride. Methylene chloride
degradation caused carbon deposition on the surfaces of
the elemental silicon and copper catalyst, which deactivated
the solid reactants. Similar difficulty was encountered in
another study, but methylene chloride decomposition was
*Corresponding authors. E-mail: injungk@korea.ac.kr; sangok@
korea.ac.kr.
(1) (a) Seyferth, D. Inorganic and Organometallic Polymers; ACS
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R. M.; Babonneau, F. Chem. Mater. 1993, 5, 260.
1
0
avoided by adding HCl to produce carbosilanes (see eq 1).
(2) (a) Bobrovsky, A. Y.; Pakhomov, A. A.; Zhu, X.-M.; Boiko, N. I.;
Shibaev, V. P.; Stumpe, J. J. Phys. Chem. B 2002, 106, 540. (b) Li, C. F.;
Jin, F.; Dong, X. Z.; Chen, W. Q.; Duan, X. M. J. Lumin. 2007, 127, 321.
Cu-Cd
Si þ CH2Cl2=HCl
ðCl2HSiÞ CH2
(3) (a) Ohshita, J.; Matsuguchi, A.; Furumori, K.; Hong, R. F.;
2
Ishikawa, M. Macromolecules 1992, 25, 2134. (b) Brefort, J. L.; Corriu,
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Garnler, F.; Yassar, A. Organometallics 1992, 11, 2500.
þ Cl2HSiCH2SiCl3 þ ðCl3SiÞ CH2 þ others ð1Þ
2
Although the preparation of cyclic and linear carbosilanes
has been achieved to some extent by direct synthesis, there is
growing demand for the development of a rational synthesis
of carbosilanes for the larger scale production of specific
(
4) (a) Son, H. J.; Han, W. S.; Lee, K. H.; Jung, H. J.; Lee, C. M.; Ko,
J.; Kang, S. O. Chem. Mater. 2006, 18, 5811. (b) Ohshita, J.; Takata, A.;
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1
9, 4492. (c) Lee, T.; Jung, I.; Song, K. H.; Baik, C.; Kim, S.; Kim, D.; Kang,
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(
5) (a) Petrov, A. D.; Mironov, V. F.; Ponomarenko, V. A.; Chemyshev,
E. A. Synthesis of Organosilicon Monomers; Consultants Bureau: New York,
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512, 131.
1
Elsevier: New York, 1967. (c) Lewis, K. M.; Rethwisch, D. G. Catalyzed Direct
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r 2010 American Chemical Society
Published on Web 01/05/2010
pubs.acs.org/Organometallics

6
88 Organometallics, Vol. 29, No. 3, 2010
Hong et al.
silanes. Among the few potential synthetic methods avail-
Scheme 1. TBPC-Catalyzed Reaction of 1 with Benzyl Chloride
able, the catalytic Si-C coupling reaction appears to be the
1
1
most desirable. Indeed, a new type of phosphine-catalyzed
Si-C coupling reaction of di- or trichlorosilane with alkyl
chlorides was determined for the formation of the corre-
sponding carbosilanes. A wide range of carbosilanes,
which would have been unobtainable from the direct
1
2
method, were prepared using this method. Based on pro-
duct isolation, phosphine-catalyzed carbosilane generation
facilitated dichlorosilylene insertion into the Si-C bond of
alkyl chlorides. For example, in the case of HSiCl , the initial
3
þ
-
ion pair formation of [Bu P] [HSiCl ] , followed by dehy-
4
4
drochlorination, was proposed to give a dichlorosilylene
intermediate, [:SiCl ], which was then inserted into the C-Cl
þ
Bu P] Cl [(tetrabutyl)phosphonium chloride, TBPC] with
4
-
[
2
C H CH Cl (benzyl chloride) at 180 ꢀC for 2 h. Instead, the
6
5
2
bond of the alkyl chlorides to give the corresponding carbo-
1
silanes.
2
reaction gave cyclic (2) and linear carbosilanes (3) and
C H CH SiCl in 47%, 16%, and 21% yield, respectively
6
5
2
3
The high yield and facile conversion to carbosilanes by
phosphine-catalyzed Si-C coupling prompted us to expand
the scope of dehydrochlorination to the reaction of bissilyl-
methane. A preliminary reaction involving HCl SiCH SiCl
(
see Scheme 1).
Since C H CH SiCl was the coupled product between
6
5
2
3
1
2b
C H CH Cl and dichlorosilylene,
6
it was assumed that
5
2
2
2
3
10
activation of compound 1 involved the generation of dichlo-
rosilylene (A) (see Scheme 2). Isolation of cyclic carbosilane
(2) as a major product strongly suggested other reaction
sequences involving different intermediates. As shown in
Scheme 2, adequate reasoning for the formation of com-
pound 2 led to the suggestion of a dichlorosilene intermedi-
ate (B). It was postulated that such a dichlorosilene
intermediate (B) dimerized in a head-to-tail manner to form
(
coupled product was not produced; instead, cyclic and linear
1) and benzyl chloride showed that the expected Si-C
8
carbosilanes, (Cl SiCH ) (2) and (CH SiCl ) SiCl (3),
2
2 2
2
3 2
2
1
4
were isolated. This suggests that there are reaction paths
involving different intermediates. Therefore, in light of the
formation of cyclic and linear carbosilanes, compounds 2
and 3, 1 was examined by different trapping experiments to
determine the possible intermediates associated with a new
reaction mechanism. Indeed, the trapping experiments of
compound 1 with 2,3-dimethylbutadiene and methylene
chloride revealed a dichlorosilylene intermediate (A) from
the isolation of 1,1-dichloro-3,4-dimethylsilacyclopent-
[
Cl Si(μ-CH ) SiCl ] (C) due to the unstable nature of the
2 2 2 2
15
SidC double bond. Further to the high ring strain of
disilacyclobutane (C), after adding dichlorosilene (B), the
reaction proceeded to give a cyclic carbosilane (2). On the
other hand, the insertion of dichlorosilylene (A) to disilacy-
clobutane (C) resulted in the formation of a linear carbosi-
lane (3). During this insertion, further ring-opening was expec-
3
-ene (5) and bis(trichlorosilyl)methane (6), respectively.
Furthermore, another intermediate, dichlorosilene (B), was
proposed on the basis of the product isolation of cyclic
carbosilane (2). To further confirm the generality of the
new mechanism with the proposed dual intermediates, a
series of bissilylmethane derivatives, HCl SiCH SiX X Cl
0
ted to give a product (3 ) terminated by a Si-H unit. The
isolation of compound 3 confirmed its origin from a facile
1
6
Si-H/Si-Cl exchange reaction, as shown in Scheme 4.
Figure 1 shows the geometry of compound 2 determined
2
2
1
2
[
X =H, X =Cl (7); X =Me, X =Cl (8); X , X =Me (9)],
1 2 1 2 1 2
17
from a X-ray structural study, where each silicon atom is
was studied for phosphine-catalyzed reactions to determine
if the involvement of the dual intermediates, dichlorosilene
bonded to a methylene unit in an alternating manner to form
a six-membered cyclic ring. The trisilacyclohexane ring
adopts a stable chair conformation with three dichloro silene
units. Table 1 summarizes the selected bond distances and
angles. No anomalies were found in both the bond distances
and angles in the carbosilane ring.
(
B) and dichlorosilylene (A), was responsible for the genera-
tion of cyclic and linear carbosilanes (2 and 3). It was also
found that substituents at the silicon atom dictated the
formation of carbosilanes. Chlorine substituents at the sili-
con atom facilitated the phosphine-catalyzed Si-C coupling
reaction, as found in compounds 7 and 8. However, the
expected reaction did not proceed when the methyl group
replaced chloride, as observed with compound 9.
To corroborate the plausible reaction sequence, the first
1
8
trapping experiment with 2,3-dimethylbutadiene was car-
ried out under identical reaction conditions. As a result, only
the dichlorosilylene (A) trapped product, 1,1-dichloro-3,4-
1
2a
dimethylsilacyclopent-3-ene (5), was isolated, as shown in
Scheme 5. The isolation of compound 5 provided direct
evidence of the involvement of the dichlorosilylene inter-
mediate (A). The typical product yields for compounds 2, 3,
Results and Discussion
The expected coupled product, C H CH SiCl CH SiCl ,
6
5
2
2
2
3
was not detected when HCl SiCH SiCl (1) was activated
2
2
3
thermally in the presence of a catalytic amount (10 mol %) of
(
15) (a) Irwin, R. M.; Cooke, J. M.; Laane, J. J. Am. Chem. Soc. 1977,
(
11) Cho, Y. S.; Kang, S. H.; Han, J. S.; Yoo, B. R.; Jung, I. N. J. Am.
Chem. Soc. 2001, 123, 5584.
12) (a) Kang, S. H.; Han, J. S.; Lee, M. H.; Yoo, B. R.; Jung, I. N.
99, 3273. (b) Auner, N.; Grobe, J. J. Organomet. Chem. 1981, 222, 33.
(c) Nametkin, N. S.; Vdovin, V. M.; Zav'yalov, V. I.; Grinberg, P. L. Izv.
Akad. Nauk. SSSR, Ser. Khim. 1965, 5, 929.
(
Organometallics 2003, 22, 2551. (b) Kang, S. H.; Han, J. S.; Yoo, B. R.; Lee,
M. S.; Jung, I. N. Organometallics 2003, 22, 529. (c) Kang, S. H.; Han, J. S.;
Lim, W. C.; Jung, I. N.; Lee, M. E.; Yoo, B. R. Organometallics 2006, 25,
(16) Jung, I. N. et al. Unpublished results for the phosphine-catalyzed
Si-H/Si-Cl exchange reactions.
(17) Fritz, G.; Matern, E. Carbosilanes: Synthesis and Reactions;
Springer: New York, 1986; p 218.
318.
(
13) Jung, I. N.; Yeon, S. H.; Han, J. S. Organometallics 1993, 12,
(18) (a) Dzarnosik, J.; Rickborn, S. F.; O’Neal, H. E.; Ring, M. A.
Organometallics 1982, 1, 1217. (b) Rogers, D. S.; O'Neal, H. E.; Ring, M. A.
Organometallics 1986, 5, 1467.
2
360.
(
14) Firtz, G. Angew. Chem., In. Ed. Engl. 1987, 26, 1111.

Article
Organometallics, Vol. 29, No. 3, 2010 689
Scheme 2. Formation of Dichlorosilylene (A) and Dichlorosilene (B) Intermediates
Table 1. Selected Bond Lengths and Angles of Compound 2
˚
Bond Lengths (A)
C(1)-Si(2)
C(2)-Si(3)
C(3)-Si(3)
1.852(3)
1.858(3)
1.854(3)
C(1)-Si(1)
C(2)-Si(2)
C(3)-Si(1)
1.854(3)
1.859(3)
1.855(3)
Bond Angles (deg)
Si(2)-C(1)-Si(1)
Si(3)-C(3)-Si(1)
115.7(2)
116.4(2)
Si(3)-C(2)-Si(2)
C(1)-Si(1)-C(3)
114.5(2)
110.4(1)
Scheme 5. TBPC-Catalyzed Reaction of 1 with
,3-Dimethylbuta-1,3-diene
2
Figure 1. X-ray structure of compound 2 with thermal ellip-
soids at the 30% probability level. Hydrogen atoms are omitted
for clarity.
Scheme 3. Proposed Mechanism for the Formation of
0
Table 2. Result of Various Dichlorosilylene (A)
Trapping Experiments
Trisilacyclohexane (2) and Trisilapentane (3 )
products
others (%)
2
(%) (%) product (%) 1 boiler materials
3
trapped
low- polymeric
trapping agents
benzyl chloride
47 16 4 (21)
9
3
6
4
3
8
6
2,3-dimethylbutadiene 42
methylene chloride 54
6
8
5 (17)
6 (23)
20
8
0
Scheme 4. Facile Si-H/Si-Cl Exchange Reaction of 3 and
3
with HSiCl
3
Scheme 6. TBPC-Catalyzed Reaction of 1 with
Methylene Chloride
and 5 from the trapping reaction with 2,3-dimethylbutadiene
were 42%, 6%, and 17%, respectively. Although 2,3-di-
Table 2 lists the results of the trapping experiments involving
dichlorosilylene (A).
1
9
methylbutadiene is a good trapping agent for silenes, the
existence of another intermediate, dichlorosilene (B), was
not confirmed. As a result, a second trapping reaction was
carried out using methylene chloride. Similar to the prece-
dent trapping reaction, the dichlorosilylene (A) trapped
To demonstrate the involvement of the dichlorosilene
intermediate (B), another trapping experiment was carried
2
out with Me SiOMe under identical reaction conditions.
0
3
However, neither the expected directly trapped product,
Me SiCH SiCl OMe, nor the indirectly related side product,
MeSiCl , was detected. It was assumed that in the course of
3
2
2
product, Cl SiCH SiCl (6), was obtained only in 23% yield
3
2
3
3
along with the cyclic and linear products 2 (54%) and 3 (8%).
Although dichlorosilene (B) was not trapped and isolated,
the trapping experiment the dichlorosilene intermediate (B)
reacts readily with gaseous HCl to give MeSiCl . However,
3
even MeSiCl was not detected in the reaction mixture.
3
Despite the lack of both direct and indirect evidence for
(19) (a) Berry, M. B.; Griffiths, R. J.; Sanganee, M. J.; Steel, P. G.;
Whelligan, D. K. Org. Biomol. Chem. 2004, 2, 2381. (b) Brook, A. G.;
Vorsphol, K.; Ford, R. R.; Hesse, M.; Chatterton, W. J. Organometallics
1987, 6, 2128.
(20) Davidson, I. M. T.; Wood, I. T. Chem. Commun. 1982, 550.

6
90 Organometallics, Vol. 29, No. 3, 2010
Scheme 7. TBPC-Catalyzed Reaction of Various Bissilylmethanes
Hong et al.
the formation of dichlorosilene intermediate (B) in this series
of trapping experiments, the formation of the cyclic-trime-
rized product, 2, suggested the involvement of the dichloro-
silene intermediate (B).
liquids were transferred using standard syringe or double-tipped
needle techniques. The bissilylmethanes were prepared using
2
1
1
0,13
the same method reported in the literature.
The reaction
mixtures were analyzed by GLC over a 1.5 mꢀ1/8 in. stainless
steel column packed with packing materials (10% SE-30 or SE-
5
Finally, HCl SiCH SiCl (1) was reacted in the presence of
3
2
2
4 on 80-100 mesh Chromosorb P/AW) using a Varian 3300
a catalytic amount (10 mol %) of TBPC without a trapping
reagent at 180 ꢀC for 3 h, yielding compound 2 as the major
product and compound 3, low-molecular weight silanes, and
viscous polymeric materials obtained as minor products. As
shown in Scheme 7, a series of bissilylmethane derivarives,
HCl SiCH SiX X Cl [X =H, X =Cl (7); X = Me, X =
gas chromatograph equipped with a thermal conductivity de-
tector and a Varian 4290 integrator. The progress of the reac-
tions was monitored by GLC at 30 min or 1 h time intervals. The
samples for characterization were purified by preparative GLC
using a Varian Aerograph series 1400 gas chromatograph with a
thermal conductivity detector and a 4 mꢀ1/8 in. stainless steel
column packed with 15% SE-30 or SE-54. The product yields
were determined by isolation or GLC using n-dodecane as the
2
2
1
2
1
2
1
2
Cl (8); X , X =Me (9)] was attempted in place of compound
1
2
1
as a variation of the phosphine-catalyzed Si-C coupling
1
13
reactions. A phosphine-catalyzed reaction involving com-
pound 7 yielded compounds 2 and 3, which was consistent
with the result of compound 1. However, compound 8
produced compounds 2 and 3 in lower yield when one
chloride ion at the silicon atom of the bissilylmethane was
replaced with one methyl group. Furthermore, compound 9
did not undergo a similar dehydrochlorinative reaction
under the same reaction conditions when two methyl groups
at the silicon atom were replaced with two chlorides. The
differences in reactivity between bissilylmethanes 7-9 might
be related to the electron -donating effect of the methyl
groups at the silicon atom due to the difficulty of chloride
ion migration to the phosphine cation.
internal standard. The H and C NMR spectra were recorded
on a Varian Mercury 300 spectrometer operating at 300.1 and
7
5.4 MHz, respectively. The chemical shifts are given in ppm rela-
tive to the residual proton signal of the solvent (CDCl 7.25 ppm
77.0 ppm ( C)) and then referenced to Me Si
0.00 ppm). Elemental analyses were performed using a Carlo
3
1
13
(
(
H) and CDCl
3
4
Erba Instruments CHNS-O EA 1108 analyzer. High-resolution
tandem mass spectrometry (Jeol LTD JMS-HX 110/110A) was
performed at the Seoul Branch of the Korean Basic Science
Institute. The GC/MS data were obtained using an Agilent
7000A Triple Quadrupole GC/MS system. The preliminary
examination and data collection were performed using a Bruker
SMART CCD detector system single-crystal X-ray diffracto-
meter equipped with a sealed-tube X-ray source (50 kVꢀ30 mA)
˚
and graphite-monochromated Mo KR radiation (λ=0.71073 A).
Conclusions
The preliminary unit cell constants were determined using a set
of 45 narrow-frame (0.3ꢀ in ω) scans. The double-pass method of
scanning was used to exclude noise. The frames collected were
integrated using an orientation matrix determined from the
narrow-frame scans. The SMART software package was used
for data collection, and SAINT was used for frame integra-
This paper described the unexpected phosphine-catalyzed
Si-C coupling reaction of compound 1 affording cyclic and
linear carbosilanes, compounds 2 and 3. The formation of
compounds 2 and 3 suggested the concurrent generation of two
silene intermediates, dichlorosilylene (A) and dichlorosilene (B).
The isolation of cyclic and linear carbosilanes suggested the
initial formation of [Cl Si(μ-CH ) SiCl ] (C) from the head-
2
2a
tion. The final cell constants were determined from a global
refinement of the xyz centroids of the reflections harvested from
the entire data set. The structure solution and refinement were
2
2 2
2
22b
performed using the SHELXTL-PLUS software package.
Preparation of (Dichlorosilyl)(trichlorosilyl)methane (1).
to-tail dimerization of dichlorosilene (B). Either cyclic (2) or
linear (3) carbosilane was produced depending on the second
addition of the silene intermediates. From a series of Si-C
coupling reactions with bissilylmethanes (7-9), there appeared
to be a general substituent effect, where a chlorine substituent at
the silicon atom was found to be most effective.
1
0
A
mixture of metallic silicon (360 g, 100-325 mesh) and 40 g of
copper catalyst was placed in the reactor made from a Pyrex
glass tube, 50 mm in internal diameter and 400 mm in length,
and electrical heating wire coiled outside and equipped with a
spiral band agitator. The mixture was dried at 300 ꢀC for 5 h with
stirring with a dry nitrogen flush. The temperature was then
increased to 350 ꢀC, and methyl chloride was introduced at
Experimental Section
2
40 mL/min to activate the contact mixture for 4 h. After remo-
General Comments. All reactions were carried out using flame-
dried glassware or in a stainless steel bomb. All air-sensitive
ving the products formed during the activation process, such as
dichlorodimethylsilane and methyltrichlorosilane, 2.0 g of cad-
mium as a promoter was added to the reactor at room tempera-
ture. The temperature was then increased to 280 ꢀC, and
methylene chloride was introduced into the evaporator using a
syringe pump attached to the bottom of the reactor at a rate
of 13.6 g/h. At the same time, gaseous hydrogen chloride was
(
21) Shriver, D. F.; Drezdon, M. A. Manipulation of Air-Sensitive
Compounds, 2nd ed.; Wiley: New York, 1986.
22) (a) SMART and SAINT; Bruker Analytical X-Ray Division:
(
Madison, WI, 2002. (b) Sheldrick, G. M. SHELXTL-PLUS Software
Package; Bruker Analytical X-Ray Division: Madison, WI, 2002.

Article
Organometallics, Vol. 29, No. 3, 2010 691
introduced at a rate of 240 mL/min (mole ratio of dichloro-
methane:hydrogen chloride was 1:4). Approximately 2 min after
starting the reaction, the reaction temperature increased slightly
due to the exothermic nature of the reaction, and the liquid
product was then collected in the receiver. After a 2 h reaction,
was separated from the catalyst by filtration. The filtrates were
separated by bulb-to-bulb vacuum distillation to give a mix-
ture of compounds 2, 3, and bis(trichlorosilyl)methane (6) (170-
180 ꢀC/10 Torr). The mixture of compounds 2, 3, and bis(trichlo-
rosilyl)methane was dissolved in hexane and recrystallized at 0 ꢀC
to give compound 2 as a white solid (54%) and a mixture of
compounds 3 and bis(trichlorosilyl)methane as a colorless liquid.
Further vacuum distillation gave compound 3 (8%) and bis(tri-
45.6 g of the products was collected in the receiver cooled to -20 ꢀC
and 46.4 g of low boilers were collected in a dry ice-acetone
trap. Gas chromatography showed that the low boilers trapped
contained a 20:1 mixture of trichlorosilane and tetrachlorosi-
lane. The product (45.6 g) was distilled at atmospheric pressure
to give 15.5 g of trichlorosilane, 1.3 g of tetrachlorosilane, and
1
chlorosilyl)methane (23%). Data for bis(trichlorosilyl)methane: H
1
3
NMR (CDCl ) δ1.86 (s, 2H, Si-CH -Si); CNMR(CDCl ) δ22.4.
3
2
3
Reaction of (Dichlorosilyl)(trichlorosilyl)methane (1) in the
Presence of TBPC. Compound 1 (500 g, 2 mol) and TBPC in
50% toluene (82.6 g, 0.2 mol) were added to a 10 L stainless steel
autoclave under a dry nitrogen atmosphere. After sealing the
tube with a cap, the reaction mixture was heated to 180 ꢀC for
3 h. After cooling, the reaction mixture was transferred to a 2 L
one-necked flask with a double-tipped needle. The mixture
consisted of two layers of an organic phase and catalyst. The
reaction mixture was separated from the catalyst by filtration.
The filtrates were separated by bulb-to-bulb vacuum distillation
to give a mixture of compounds 2 and 3 (64%, 170-180 ꢀC/10
Torr). The mixture of compounds 2 and 3 was dissolved in
hexane and recrystallized at 0 ꢀC to give compounds 2 and 3 as a
white solid (50%) and colorless liquid (14%), respectively.
Reaction of Bis(dichlorosilyl)methane (7) in the Presence of
TBPC. The procedure was similar to that described for the
reaction of (dichlorosilyl)(trichlorosilyl)methane (1) in the pre-
sence of TBPC. Bis(dichlorosilyl)methane (7) (6.8 g, 32 mmol)
and TBPC in 50% toluene (0.9 g, 3 mmol) were added to a 25 mL
stainless steel tube under a dry nitrogen atmosphere. After
sealing the tube with a cap, the reaction mixture was heated to
180 ꢀC for 3 h. The reaction mixture was cooled and separated
from the catalyst by filtration. The filtrates were separated by
bulb-to-bulb vacuum distillation to give a mixture of 2 and 3
(170-180 ꢀC/10 Torr). The mixture compounds of 2 and 3 was
dissolved in hexane and recrystallized at 0 ꢀC to isolate 2 as a
white solid (59%) and 3 as a colorless liquid (9%).
Reaction of (Methyldichlorosilyl)(dichlorosilyl)methane (8) in
the Presence of TBPC. The procedure was similar to that
described for the reaction of (dichlorosilyl)(trichlorosilyl)methane
(1) in the presence of TBPC. (Methyldichlorosilyl)(dichlorosilyl)-
methane (8) (7.3 g, 32 mmol) and TBPC in 50% toluene (0.9 g,
3 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 to 180 ꢀC for 3 h. After cooling, the
reaction mixture was separated from the catalyst by filtration. The
filtrates were separated by bulb-to-bulb vacuum distillation to give
a mixture of 2 and 3 (170-180 ꢀC/10 Torr). The mixture com-
pounds of 2and 3was dissolved in hexane and recrystallized at 0 ꢀC
to isolate 2 as a white solid (37%) and 3 as a colorless liquid (8%).
Reaction of (Dimethylchlorosilyl)(dichlorosilyl)methane (9) in
the Presence of TBPC. The reaction procedure was similar to
that described for the reaction of (dichlorosilyl)(trichlorosilyl)-
methane (1) in the presence of TBPC. (Dimethylchlorosilyl)-
(dichlorosilyl)methane (9) (6.6 g, 32 mmol) and TBPC in 50%
toluene (0.9 g, 3 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 to 180 ꢀC for 3 h. After
cooling, the reaction mixture was separated from the catalyst by
filtration. GC analysis showed that no reaction had occurred.
0
.5 g of methylene chloride. Distillation was continued under
vacuum to give 10.1 g of (trichlorosilyl)(dichlorosilyl)methane,
.7 g of compound 1, and 2.0 g of bis(trichlorosilymethane. The
8
residue was distilled bulb to bulk to give 6.9 g of a mixture of
high-boiling products but negligible quantities of nondistillable
polymeric materials. GC-MS analysis of the high-boiling pro-
ducts showed that they contained linear and cyclic carbosilanes
7
with silicon-hydrogen bonds, as reported previously. Bis-
1
(
1
1
dichlorosilylmethane): bp 146-147 ꢀC; H NMR (CDC1
3
) δ
1
3
.40 (t, 2H, CH ); 5.71 (t, 2H, Si-H); C NMR (CDC1 ) δ 14.42.
2 3
1
: bp 165-166 ꢀC; H NMR (CDCl ) δ 1.64 (d, 2H, CH ); 5.72
3
2
13
(
t, 1H, Si-H); C NMR (CDCl
3
) δ 18.6. (Trichlorosilylmethyl)-
1
trichlorosilane: bp 179-180 ꢀC; H NMR (CDCl
CH ); C NMR (CDCl ) δ 22.5.
3
) δ 1.88 (s,
13
2
3
Reaction of (Dichlorosilyl)(trichlorosilyl)methane (1) with Ben-
zyl Chloride in the Presence of TBPC. Compound 1 (7.5 g, 30
mmol), benzyl chloride (3.8 g, 30 mmol), and TBPC in 50%
toluene (0.9 g, 3 mmol) were added to a 25 mL stainless steel tube
under a dry nitrogen atmosphere. After sealing the tube with a
cap, the reaction mixture was heated to 180 ꢀC for 2 h. After
cooling, the reaction mixture was transferred to a 100 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 separated from the catalyst by filtration. The
filtrates were separated by bulb-to-bulb vacuum distillation at
1
1
40-142 ꢀC/10 Torr to give the benzyl chloride (4) (21%) and at
70-180 ꢀC/10 Torr to give a mixture of compounds 1,1,3,3,5,5-
hexachloro-1,3,5-trisilacyclohexane (2) and 1,1,1,3,3,5,5,5-octa-
chloro-1,3,5-trisilapentane (3). A mixture of compounds 2 and 3
was dissolved in hexane and then recrystallized at 0 ꢀC to isolate 2
as a white solid (47%) and 3 (16%) as a colorless liquid. Data for
1
13
C
compound 2: H NMR (CDCl
NMR δ 17.4. Data for compound 3: H NMR (CDCl ) δ 1.71 (s,
3
) δ 1.46 (s, 6H, Si-CH
2
-Si);
1
3
13
4
H, Si-CH
2
-Si); C NMR δ 20.3. Data for benzyltrichlorosilane:
H NMR (CDCl ) δ 2.92 (s, 2H, Si-CH -C), 7.31 (m, 5H, Ar-H);
3
1
3
2
1
C NMR (CDCl ) δ 32.9, 126.5, 128.8, 129.3, 132.0.
3
Reaction of (Dichlorosilyl)(trichlorosilyl)methane (1) with 2,3-
Dimethylbutadiene in the Presence of TBPC. Compound 1 (7.5 g,
3
5
0 mol), 2,3-dimethylbutadiene (2.5 g, 30 mmol), and TBPC in
0% toluene (0.9 g, 3 mmol) was 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 to 180 ꢀC for 3 h. The
filtrates were separated by bulb-to-bulb vacuum distillation to
give a mixture of compounds 2 and 3 (170-180 ꢀC/10 Torr) and
1
1
,1-dichloro-3,4-dimethylsilacyclopent-3-ene (5) (133 ꢀC/10 Torr,
7%). The mixture of compounds 2 and 3 was dissolved in hexane
and recrystallized at 0 ꢀC to give compound 2 as a white solid
42%) and 5 as a colorless liquid (6%). Further vacuum distilla-
tion gave compounds 3 (6%) and 5 (17%). Data for compound 5:
(
1
13
C
H NMR (CDCl
3
) δ 1.75 (s, 6H, CH
3
), 1.88 (d, 4H, CH
2
);
NMR (CDCl ) δ 19.2, 29.6, 129.8.
Reaction of (Dichlorosilyl)(trichlorosilyl)methane (1) with Methyl-
ene Chloride in the Presence of TBPC. Compound 1 (12.4 g,
Acknowledgment. This study was supported by a Nati-
onal Research Foundation of Korea (NRF) grant funded
by the Korea government (MEST) (No. 2009-0083181)
and the Korea Institute of Science and Technology.
3
5
0 mol), methylene chloride (2.9 g, 26 mmol), and TBPC in 50%
toluene (1.5 g, 5 mmol) was 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 to 180 ꢀC for 3 h.
After cooling, the reaction mixture was transferred to a 100 mL
one-necked flask with a double-tipped needle. The reaction mixture
Supporting Information Available: Tables and figure showing
the X-ray crystallographic details for compound 2 and the
spectroscopic data for the materials. This material is available
free of charge via the Internet at http://pubs.acs.org.