Synthesis and reactivity of bis(triethoxysilyl)methane, tris(triethoxysilyl)methane and some derivatives

Article abstract of DOI:10.1016/S0022-328X(98)00365-9

Syntheses of new poly(trifunctional-silyl)alkanes, which are potent coupling agents of hybrid organic-inorganic materials have been thoroughly examined. Optimization of the Benkeser reaction using chloroform, trichlorosilane and tri-n-butylamine (respective ratios 1:4.5:3) afforded bis(trichlorosilyl)methane isolated as bis(triethoxysilyl)methane after ethanolysis (overall yield 60%). With nine equivalents of trichlorosilane, tris(trichlorosilyl)methane is preferentially formed, isolated as tris(triethoxysilyl)methane (30% yield). C-Substituted bis(triethoxysilyl) methanes were obtained after metallation of the α-carbon and trapping experiments with the corresponding alkyl halides. In the case of tris(triethoxysilyl)carbanion, only MeI and Br₂ were able to give the anticipated products. Unexpectedly, CO₂ insertion afforded the stable ketene, [(EtO)₃Si]₂C=C=O.

Full text of DOI:10.1016/S0022-328X(98)00365-9

Journal of Organometallic Chemistry 562 (1998) 79–88
Synthesis and reactivity of bis(triethoxysilyl)methane,
tris(triethoxysilyl)methane and some derivatives1
Robert J.P. Corriu *, Michel Granier, Ge´rard F. Lanneau
Laboratoire de Chimie Mole´culaire et Organisation du Solide, UMR 5367-Pre´curseurs Organo Me´talliques de Mate´riaux, Uni6ersite´ Montpellier II,
Case 007, Place Euge`ne Bataillon, 34095 Montpellier Cedex 05, France
Received 26 July 1997
Abstract
Syntheses of new poly(trifunctional-silyl)alkanes, which are potent coupling agents of hybrid organic–inorganic materials have
been thoroughly examined. Optimization of the Benkeser reaction using chloroform, trichlorosilane and tri-n-butylamine
(respective ratios 1:4.5:3) afforded bis(trichlorosilyl)methane isolated as bis(triethoxysilyl)methane after ethanolysis (overall yield
60%). With nine equivalents of trichlorosilane, tris(trichlorosilyl)methane is preferentially formed, isolated as tris(triethoxysi-
lyl)methane (30% yield). C-Substituted bis(triethoxysilyl) methanes were obtained after metallation of the h-carbon and trapping
experiments with the corresponding alkyl halides. In the case of tris(triethoxysilyl)carbanion, only MeI and Br2 were able to give
the anticipated products. Unexpectedly, CO2 insertion afforded the stable ketene, [(EtO)3Si]2CꢀCꢀO. © 1998 Elsevier Science S.A.
All rights reserved.
Keywords: Gem-bis(triethoxysilyl)alkanes; Bis(triethoxysilyl)carbanion; Tris(triethoxysilyl)carbanion; Bis(triethoxysilyl)ketene
1. Introduction
trifunctional-organosilanes [9]. The monomers, with
formula R%SiX3 (X=Cl, OR, H) with non-labile Si–R%
groups (R%=alkyl, aryl, etc.) and hydrolyzable Si–X
bonds have been widely described [10], and many of
these molecules are commercially available. Different
final forms of the solid, such as gels, colloidal materials
or precipitates can be observed [11]. If the R% group
presents a terminal reactive carbon center, organic
chemistry can be performed for anchoring to the or-
ganic part of the hybrid material [12].
In a somewhat more direct approach, polydentate
hybrid organic–inorganic xerogels [13–15] were di-
rectly synthesized in mild conditions from molecules
such as bis(trialkoxysilanes), (R%O)3Si–R–Si(OR%)3.
These molecules, by hydrolysis of their functions –OR%,
give silanols, which condense to give siloxanes of gen-
eral formula O1.5Si–R–SiO1.5. Successive condensa-
tions afford a three dimensional hybrid network, in
which the organic part is embedded inside the matrix. It
has been observed that the formation of the solid is
Hybrid organic–inorganic polymers have found re-
cent applications in surface science, ceramic precursors,
optics and electronic devices. Either used as coatings or
combined in the bulk of the material, their structure
allowed to incorporate many organic moieties with
specific properties and functionalities in inorganic mate-
rials at the nano-size level [1–7].
The recently developed sol–gel process applied to
organosilicon species offered a mild approach to the
synthesis of hybrid materials with interfacial interac-
tions and domain sizes approaching the molecular level
[8]. Among them, silsesquioxanes, with the empirical
formula of R%SiO1.5, were initially obtained by the
carefully controlled hydrolysis/condensation steps of
* Corresponding author. Fax: +33 046743852.
1 Dedicated to Prof. R. Bruce King, on the occasion of his 60th
birthday, in recognition of his outstanding contribution to
organometallic chemistry.
0022-328X/98/$19.00 © 1998 Elsevier Science S.A. All rights reserved.
PII S0022-328X(98)00365-9

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R.J.P. Corriu et al. / Journal of Organometallic Chemistry 562 (1998) 79–88
Scheme 1.
much more easy with these polysilylated precursors
than with the monosilylated ones [16,17].
more specific results were obtained in the case of Mg/
Zn coupling reaction of Me3SiCl with CH2Cl2, in THF
[22]. Their extension to the synthesis of ꢁC(SiRX2)2 or
ꢁC(SiX3)2 seemed difficult, essentially due to further
reactions, with for example polyadditions, intramolecu-
lar eliminations and rearrangements [23]. Disilyl-
methanes with functional groups at silicon were
obtained from Me3SiCH2SiMe3 by selective cleavage of
methyl ligand by AlCl3/RCOCl [24], or Me3SiCl with
AlCl3. Some other methods can be found in the litera-
ture, but their absence of selectivity prevents their
utilization on a large scale [25]. The chemistry of com-
pounds in which three organosilyl groups are attached
to a central carbon atom has been reviewed [26].
We already described three methods in order to
access such compounds: addition of Grignard reagents
to vinylsilanes [27] (eq 1), metallation of chloromethy-
lalkoxysilanes [28] (eq 2), or the Heck reaction applied
to unsaturated organosilanes [29] (eq 3). However, the
presence of alkoxy substituents on the silicon atom
induced the easy cleavage of the silicon–carbon bonds
of (RO)X2SiCH2Y derivatives with oxidants [30].
Most of the studies of coupling agents found in the
literature for bonding between organic polymer and
inorganic counterpart have been performed with mono-
organosilanes [18]. Optimization of the silane to sub-
strate interface is a key factor in the control of their
properties [19].
The aim of the present work is the elaboration of
new synthons in the series of mono-organosilsesquiox-
anes with organic chains specifically bis-endcapped or
tris-endcapped with tris-alkoxysilyl groups in order to
produce efficient coupling agents able to create strong
covalent bonds between the different phases (Scheme
1).
Different methods, available for the preparation of
carbosilanes, are well documented in the case of
ꢁC(SiR3)2 or ꢁC(SiR2X)2 derivatives [20]. For exam-
ple, it has been reported that addition of n-BuLi to cold
solutions of methylene chloride and trimethylchlorosi-
lane in THF/hexane leads to a complexed product
mixture of mono-, di- and tri-silylmethanes [21]. Some

R.J.P. Corriu et al. / Journal of Organometallic Chemistry 562 (1998) 79–88
81
Table 1
Coupling reactions of ClSi(OEt)a3 with CHxX4−x
No.
1
CHxX4−x
CHBr3
M
Solvent
Conditionsb
A
Si productsc
n-BuLi
ClSi(OEt)3 (6)
Si(OEt)4 (40)
n-BuSi(OEt)3 (5)
(EtO)3Si–O–Si(OEt)3 (14)
No reaction
ClSi(OEt)3 (18)
Si(OEt)4 (40)
2
3
CH2I2
CH2Br2
n-BuLi
n-BuLi
Et2O
Et2O
A
A
n-BuSi(OEt)3 (30)
(EtO)3Si–O–Si(OEt)3 (7)
No reaction
No reaction
No reaction
4
5
6
7
B
C
D
D
Mg(‡ I2)
Li
Et2O
THF
ClSi(OEt)3 (71)
Si(OEt)4 (18)
(EtO)3Si–O–Si(OEt)3 (19)
No reaction
No reaction
ClSi(OEt)3 (72)
Si(OEt)4 (21)
8
9
10
CH2Cl2
n-BuLi
Mg(‡ I2)
Li
Et2O
Et2O
THF
D
D
D
(EtO)3Si–O–Si(OEt)3 (7)
a Initial mixture of 79% ClSi(OEt)3, 18% Si(OEt)4, 1–3% Cl2Si(OEt)2.
b Experimental conditions:
(A) n-BuLi is added dropwise to a cold solution (−80°C) of chlorotriethoxysilane and halogenomethane in the proper solvent. The mixture is
warmed up to r.t. and filtered.
(B) The reaction mixture of halogenomethane/n-BuLi/Et2O maintained at −10°C, is rapidly transferred to a cold solution (−80°C) of
chlorotriethoxysilane, dissolved in THF.
(C) The stoichiometric amount of chlorotriethoxysilane dissolved in THF is added immediately to the white precipitate of CH2X2/n-BuLi/Et2O
at −80°C
(D) To magnesium/ether or lithium/THF and ClSi(OEt)3, was added dropwise a solution of halogenomethane in the proper solvent. The
mixture was then refluxed for 3 h. After work up, the solvent and organics were removed at atmospheric pressure, and fractional distillation at
reduced pressure yielded the organosilicon products, the mixture of them being analyzed by GC and 29Si-NMR.
c ‘No reaction’ means that analysis of the mixture after work up by GC and 29Si-NMR afforded only the presence of starting organosilanes,
ClSi(OEt)3 and Si(OEt)4.
Another general method of preparation of trifunc-
tional silicon-containing organic molecules involves
silylation of polyhalo compounds by the trichlorosi-
lane/amine combination developed by Benkeser et al.
(eq 4) [31]. The latter reagents also effect the reduction
of benzoic acids and some of its derivatives to benzylic
trichlorosilanes in good yields [32].
We describe here the different approaches we have
developed in order to improve the controlled syntheses
of di- or tri-silicon made precursors, affording new
synthons which could then be used as coatings in solid
materials.
bond with n-Bu(−) anion. In the case of Li/THF activa-
tion, the lithium wires were consumed with formation
of a black turbid mixture. However, the only change of
the silicon species was a small modification in the ratios
of ClSi(OEt)3, Si(OEt)4 and (EtO)2SiCl2 which moved
from the relative ratios 79:18:3 to 72:21:7, with forma-
tion of hexaethoxydisiloxane (EtO)3Si–O–Si(OEt)3.
With Mg/Et2O, no reaction was observed, despite the
fact that a precipitate of magnesium salt was present in
the mixture, corresponding to some extent of reaction
of CHnX4−n with Mg. The trimeric 1,3,5-(diethoxysila)-
cyclohexane, [(EtO)2Si–CH2]3, was characterized as the
main decomposition product of the metallation of
(EtO)3 Si–CH2Cl with Mg/THF at room temperature
(r.t.) [34]. The trimer has never been detected in the
present case by 29Si-NMR of the crude reaction mix-
tures, which indicates that (EtO)3Si–CH2MgX (respec-
tively (EtO)3Si–CH2Li) is not formed in our
experimental conditions.
2. Results and discussion
Preliminary experiments of the coupling reaction of
geminal-dilithiodiphenylmethane [33] with ClSi(OEt)3
afforded only oligomeric materials. From the reaction
of CHnX4−n with ClSi(OEt)3 in the presence of n-BuLi
(Table 1), the only product was n-BuSi(OEt)3 which
corresponds to the normal substitution of the Si–Cl
In the absence of efficient synthesis of gem-disilyl-
methanes through the metallation process, we decided
to turn our efforts to another approach. The alcoholy-

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R.J.P. Corriu et al. / Journal of Organometallic Chemistry 562 (1998) 79–88
sis of Hn+2C(SiCl3)3−n has been described [35]. Some
results have been reported concerning the synthesis of
these chlorosilylalkanes on the laboratory scale with
scarce yield [36]. In 1969, Benkeser et al. proposed a
different method of forming the silicon–carbon bond
(eq 4), based on the selective reduction of poly-halo
compounds with HSiCl3/n-Bu3N. However, if the
method was highly efficient for synthesizing benzylic
silanes and analogues, the extension to alkyl halides
and polyhalocarbons was unsuccessful, essentially due
to the reaction of trichlorosilanes with R3NHCl in the
experimental conditions (Scheme 2) [37].
We therefore decided to prepare the expected com-
pounds in two steps. Initially, we would form the
bis(trifunctional-silyl)methanes and tris(trifunctional-
silyl)methanes, which could then be metallated on the
h-carbon and trapped with the corresponding alkyl
halides (Scheme 3).
Thus, when chloroform, trichlorosilane and tri-n-
butylamine are allowed to react in the ratio 1:4.5:3,
bis(trichlorosilyl)methane is obtained in 90% yield in
the crude mixture, later isolated as bis(triethoxysi-
lyl)methane after ethanolysis (overall yield 60%). On
the other hand, if a large excess (nine equivalents) of
silicochloroform is introduced in the reaction medium,
tris(trichlorosilyl)methane is formed, isolated as tris(tri-
ethoxysilyl) methane (30%).
That result deserves some comments. The
tris(trichlorosilyl)methane was envisioned by Benkeser
et al. [38] in the reactions of trichlorosilane–tertiary
amines with organic halides (Scheme 2), but not charac-
terized even as transient species. Conditions used by
these authors supposed that cleavage of one of the
silicon–carbon bonds in tris(trichlorosilyl) methane to
obtain the bis(trichlorosilyl) derivative was a preferred
pathway under their conditions of reaction. Our proce-
dure describes the conditions affording both types of
compounds with reproducible yields.
As an example of the general protocol we have used,
0.045 mol of HSiCl3, 0.01 mol of CHCl3 and 5 ml of
freshly distilled acetonitrile were mixed at −40°C, and
tri-n-butylamine (0.03 mol) was added dropwise to
form a waxy precipitate. Warming up the turbid mix-
ture to r.t., a clean solution was obtained. The mixture
Scheme 3.
was refluxed for 16 h. After concentration in vacuo and
addition of 200 ml of pentane, emulsification was ob-
served with two phases. The lower pale white layer
contained ammonium/amine species.
At this stage, two different treatments were possible.
The upper pentane layer was first concentrated in vacuo
and distillation afforded the expected bis(trichlorosilyl)
methane in 50% yield (with some thermal decomposi-
tion). The second possibility we experienced was to
perform the alcoholysis of the pentane extract; forma-
tion of a precipitate showed that NR3 was partially
soluble in the upper mixture. After filtration, distilla-
tion afforded (EtO)3SiCH2Si(OEt)3, with 50% yield.
In a one-pot procedure, ethanolysis of the crude two
phases mixture at −40°C afforded the bis(triethoxysi-
lyl)methane with \90% purity, in the upper pentane
phase material (GC/MS). Distillation (with some de-
composition) afforded analytical sample whose charac-
teristics were comparable with those of authentic
compound [34] (overall yield 60%).
A similar procedure was followed to obtain tris(tri-
ethoxysilyl)methane from chloroform (2 mmol), HSiCl3
(18 mmol) and tri-n-butylamine (6 mmol) in 5 ml of
acetonitrile. After work up, ethanolysis with 36 mmol
Scheme 2.

R.J.P. Corriu et al. / Journal of Organometallic Chemistry 562 (1998) 79–88
83
Scheme 4. Trapping experiments with the bis(triethoxysilyl)carbanion.
of EtOH afforded the expected compound which was
isolated by distillation at 100°C (10−2 mm Hg), 30%
yield. In the first fraction, we isolated the bis(tri-
ethoxysilyl)methane (50% yield).
Metallation of bis(triethoxysilyl)methane, with t-
BuLi, in pentane/THF, was performed at −65°C in 1
h. Various electrophiles were added at that temperature
and the mixtures warmed up for an additional 3 h.
Work up afforded the products, which were analyzed
by GC/MS (Scheme 4).
Aromatic halides were unreactive with the disilyl-car-
banion, whereas strong electrophiles gave the expected
products in fairly good yields. The gem-disilylbro-
momethane afforded the expected bis(triethoxysi-
lyl)ethane by substitution with MeLi, whereas trans
metallation was observed with PhLi giving PhBr and
bis(triethoxysilyl)methane, the carbanion being trapped
by reaction with the solvent.
That rearrangement emphasizes the particular behav-
ior of the alkoxysilyl groups to induce specific reactivity
at the h-carbanion [39]. The comparison with the nor-
mal carbonation of [tris(trimethylsilyl)methyl] lithium
which affords the carboxylic acid after protonation [40],
without decomposition is typical. Interconversion of
1-trimethylsiloxy-2-silylethynes to trimethylsilyl(si-
lyl)ketenes has been recently discussed [41]. IR analysis
of the crude mixture showed that siloxyacetylene was
not present in our experimental conditions. The spec-
trum shows characteristic, strong IR absorption band
at 2110 cm−1 due to the ketene vibrations. Only one
signal at l −56.9 ppm is observed in the 29Si-NMR
spectrum and the 13C chemical shift of the sp2-hy-
bridized carbon at l 1.35 ppm is characteristic of
silylketene [42].
A similar procedure of metallation was used in the
case of tris(triethoxysilyl)methane (Scheme 5). In trap-
ping essays with PhI and PhCH2Cl, the starting mate-
rial is recovered. Only MeI and Br2 were able to give
the expected products. An unexpected reaction oc-
curred with CO2. Insertion and rearrangement afforded
the stable ketene, [(EtO)3Si]2CꢀCꢀO, which probably is
formed by intramolecular elimination of the silanolate
(Scheme 6).
3. Conclusion
The present work describes the different approaches
we have tried to optimize the elaboration of reactive
synthons in the series of mono-organosilsesquioxanes
with organic chains specifically bis-endcapped or tris-
endcapped with tris-alkoxysilyl groups. The synthesis of
gem-disilylmethanes through the metallation process
were not successful. An optimization of the Benkeser

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R.J.P. Corriu et al. / Journal of Organometallic Chemistry 562 (1998) 79–88
Scheme 5. Trapping experiments with tris(triethoxysilyl)carbanion.
reaction, based on the selective reduction of poly-halo
compounds with HSiCl3/n-Bu3N allowed to obtain
bis(trifunctional-silyl)methanes and tris(trifunctional-
silyl)methanes with yield ranging 30–80%. These com-
pounds could then be metallated on the h-carbon and
trapped with electrophiles. Aromatic halides were un-
reactive with the disilyl-carbanion, whereas strong
electrophiles gave the expected products in fair yields.
Only MeI and Br2 were able to react with tris(tri-
ethoxysilyl)carbanion. With CO2, insertion and rear-
rangement afforded the stable ketene, [(EtO)3Si]2
CꢀCꢀO.
4.1. Preparation of bis(triethoxysilyl)methane
Tri-n-butylamine (11.1 g, 60 mmol) was added drop-
wise to a mixture of chloroform (2.4 g, 20 mmol),
trichlorosilane (12.2 g, 90 mmol) and acetonitrile (5 ml)
at −40°C. The solution was allowed to warm up and
stirred overnight at 65°C. After removal of the solvent
in vacuo, pentane (50 ml) was added. To this mixture
cooled to −40°C was added ethanol (14.1 ml, 240
mmol). After warming up to r.t., extraction with pen-
tane (2×50 ml) and concentration in vacuo, the
residue was distilled at 80°C (10−2 mm Hg) giving a
1
colorless liquid (yield 60%). H-NMR (CDCl3): l −
0.03 (s, 2H, CH2Si); 1.21 (t, JHH=7.0 Hz, 18H, CH3);
3.82 (q, JHH=7.0 Hz, 12H, CH2O). 13C-NMR: l −
7.50 (CH2Si); 18.43 (CH3); 58.56 (CH2O). 29Si-NMR: l
−46.12. Mass spectrum (70 eV): m/e 295 [M+ −45
(EtO), 100%]; 267 [M+ −45 (EtO) −28 (C2H4), 64%];
163 [(EtO)3Si+, 33%]; 135 [(EtO)3Si+ −28 (C2H4),
7.7%]; 45 (EtO+, 17%). Anal. Calc. for C13H32O6Si2: C,
45.85; H, 9.47; Si, 16.49; O, 28.19. Found: C, 45.92; H,
9.52; Si, 16.56.
4. Experimental
All reactions were carried out under argon or nitro-
gen with dry solvents. H-NMR spectra were recorded
1
on a Bruker DPX 200 spectrometer with TMS as an
internal reference. 29Si and 13C-NMR spectra were
recorded on a Bruker DPX 200 or a Bruker SP 250
AC instrument. Mass spectra were recorded on a Delsi
Nermag gaz chromatograph coupled with an Auto
mass spectrometer [diphenyl (5%) dimethylsilicone as
stationary phase, electron impact mode, 70 eV] or on
a Jeol DX 300 spectrometer (electron impact mode, 70
eV). IR spectra were recorded on a Perkin Elmer 1600
spectrophotometer with polystyrene film used for cali-
bration. Elementary analysis were performed by the
‘Service Central d’Analyse du CNRS France’. Carbon
and hydrogen contents were established by high tem-
perature combustion and IR spectroscopy. Silicon con-
tents were determined by ICP atomic emission spec-
troscopy.
4.2. Preparation of tris(triethoxysilyl)methane
Tri-n-butylamine (11.1 g, 60 mmol) was added drop-
wise to a mixture of chloroform (2.4 g, 20 mmol),
trichlorosilane (24.4 g, 180 mmol) and acetonitrile (5
ml) at −40°C. The solution was allowed to warm up,
stirred overnight at r.t. for 1 h at 65°C. After removal
of the solvent in vacuo, pentane (50 ml) was added. To
the mixture cooled at −40°C was added ethanol (21.1
ml, 360 mmol). After warming up to r.t., extraction
with pentane (2×50 ml) and concentration in vacuo,

R.J.P. Corriu et al. / Journal of Organometallic Chemistry 562 (1998) 79–88
85
Scheme 6. Carbonation of tris(triethoxysilyl)carbanion.
a colorless liquid (yield 30%). 1H-NMR (CDCl3): l
−0.09 (s, 1H, CHSi); 1.22 (t, JHH=7.0 Hz, 27H, CH3);
3.87 (q, JHH=7.0 Hz, 18H, CH2O). 13C-NMR: l −
4.41 (CHSi); 18.28 (CH3); 58.58 (CH2O). 29Si-NMR: l
−49.88. Mass spectrum (70 eV): m/e 457 [M+ −45
(EtO), 100%]; 429 [M+ −45 (EtO) −28 (C2H4), 3.3%];
163 [(EtO)3Si+, 22%]; 135 [(EtO)3Si+ −28 (C2H4),
1.9%]; 45 (EtO+, 28%). Anal. Calc. for C19H46O9Si3: C,
45.39; H, 9.22; Si, 16.76. Found: C, 45.46; H, 9.27; Si,
16.65.
evaporation of the solvent, the compound was isolated
by distillation (b.p. 96–98°C, 10−2 mm Hg), 91% yield.
1H-NMR (CDCl3); l −0.42 (s, 1H, CH); 0.11 (s, 9H,
CH3Si); 1.18 (t, JHH=7.0 Hz, 18H, CH3–C); 3.81 (q,
J
HH=7.0 Hz, 12H, CH2). 13C-NMR: l −1.67 (CH);
1.94 (CH3–Si); 18.44 (C6
H3–C); 58.54 (CH2).29Si-NMR:
l −47.91 [Si(OEt)3]; 0.54 (SiMe3). Mass spectrum (70
eV): m/e 397 [M+ −15 (Me), 100%]; 367 [M+ −45
(OEt), 15%]; 163 [(EtO)3Si+, 25%]; 73 (Me3Si+, 6.4%);
45 (EtO+, 8.2%).
4.3. Synthesis of [bis(triethoxysilyl)methyl] lithium salt
4.6. Synthesis of 1,1-bis(triethoxysilyl)-2-phenylethane
To a THF solution (50 ml) of bis(triethoxysi-
lyl)methane (0.68 g, 2 mmol), at −80°C was added
dropwise the stoichiometric amount of t-BuLi in pen-
tane. After the mixture was stirred for 1 h at −65°C,
the lithium salt was ready to use.
To a solution of [bis(triethoxysilyl)methyl] lithium
salt (2 mmol, 30 ml THF) at −80°C was added benzyl
chloride (6 mmol, 0.76 g). After the solution was
warmed up to r.t. and the solvent removed, the residue
was treated with pentane and filtered. After evapora-
tion of the solvent, the compound was isolated by
distillation (b.p. 121–124°C, 10−2 mm Hg), 81% yield.
1H-NMR (CDCl3): l 0.64 (t, JHH=6.7 Hz, 1H, CH);
1.22 (t,JHH=7.0Hz, 18H,CH3); 2.97 (d ,JHH=6.7 Hz,
2H, CH2Ph); 3.82 (q, JHH=7.0 Hz, 12H, CH2O); 7.2–
7.4 (m, 5H, Harom). 13C-NMR: l 11.09 (CHSi); 18.56
(CH3); 30.11 (CH2Ph); 58.71 (CH2O); 125.79, 128.26,
129.11, 144.80 (Carom). 29Si-NMR: l −47.81. Mass
spectrum (70 eV): m/e 384 [M+ −46 (EtOH), 100%];
163 [(EtO)3Si+, 21%]; 91 (PhCH2+, 37%]; 45 (EtO+,
10%).
4.4. Synthesis of 1,1-bis(triethoxysilyl)ethane
To a solution of [bis(triethoxysilyl)methyl] lithium
salt (2 mmol, 30 ml THF) at −80°C was added methyl
iodide (6 mmol, 0.85 g). After the solution was warmed
up to r.t. and the solvent removed in vacuo, the residue
was treated with pentane and filtered. After evapora-
tion of the solvent, the product was obtained as a
1
colorless liquid (0.67 g, 95% yield). H-NMR (CDCl3):
l 0.23 (q, JHH=7.6 Hz, 1H, CH); 1.12 (d, JHH=7.6
Hz, 3H, CH3–CH); 1.19 (t, JHH=7.0 Hz, 18H, CH3
6 –
CH2O); 3.83 (q, JHH=7.0 Hz, 12H, CH2O). 13C-NMR:
4.7. Synthesis of bis(triethoxysilyl)bromomethane
l 0.34 (CH); 8.22 (C6 H3CH); 18.53 (C6 H3–CH2); 58.74
(CH2O). 29Si-NMR: l −46.02. Mass spectrum (70 eV):
m/e 309 [M+ −45 (OEt), 86%]; 281 [M+ −45 (EtO)
−28 (C2H4), 62%]; 163 [(EtO)3Si+, 54%]; 135
[(EtO)3Si+ −28 (C2H4), 100%]; 45 (EtO+, 43%).
To a solution of [bis(triethoxysilyl)methyl] lithium
salt (2 mmol, 30 ml THF) at −80°C was added
bromine (3 mmol, 0.48 g). After the solution was
warmed up to r.t. and the solvent removed, the residue
was treated with pentane and filtered. After evapora-
tion of the solvent, the compound was isolated by
distillation (b.p. 95–97°C, 10−2 mm Hg), 67% yield.
1H-NMR (CDCl3): l 1.15 (t, JHH=7.0 Hz, 18H, CH3);
2.08 (s, 1H, CH); 3.83 (q, JHH=7.0 Hz, 12H, CH2).
13C-NMR: l 10.14 (CH); 18.35 (CH3); 59.60 (CH2).
29Si-NMR: l −58.13. Mass spectrum (70 eV): m/e 373
(M+ −44, 3.0%); 375 [(M+ +2)−44, 3.1%]; 163
[(EtO)3Si+, 48%]; 45 (EtO+, 100%).
4.5. Synthesis of [bis(triethoxysilyl)](trimethylsilyl)
methane
To a solution of [bis(triethoxysilyl)methyl] lithium
salt (2 mmol, 30 ml THF) at −80°C, was added
chlorotrimethylsilane (6 mmol, 0.65 g). After the solu-
tion was warmed up to r.t. and the solvent removed,
the residue was treated with pentane and filtered. After

86
R.J.P. Corriu et al. / Journal of Organometallic Chemistry 562 (1998) 79–88
trum (70 eV): m/e 535 [M+ −45 (OEt), 5.5%]; 537
[(M+ +2)−45 (OEt), 5.7%]; 163 [(EtO)3Si+, 72%]; 45
(EtO+, 100%).
4.8. Synthesis of 1,1-bis(triethoxysilyl)tridecane
To a solution of [bis(triethoxysilyl)methyl] lithium
salt (2 mmol, 30 ml THF) at −80°C was added
1-bromododecane (4 mmol, 0.98 g). After the solution
was warmed up to r.t. and the solvent removed, the
residue was treated with pentane and filtered. After
evaporation of the solvent, the compound was isolated
by distillation (b.p. 150–160°C, 10−2 mm Hg), 21%
4.12. Synthesis of bis(triethoxysilyl)ketene
To a solution of [tris(triethoxysilyl)methyl] lithium
salt (2 mmol, 30 ml THF) at −80°C, was added a large
excess (ꢀten equivalents) of CO2 (dry ice). After the
solution was warmed up to r.t. and the solvent re-
moved, the residue was treated with pentane and
filtered. After evaporation of the solvent, the product
1
yield. H-NMR (CDCl3): l 0.18 (t, JHH=6.6 Hz, CH,
1H); 0.86 (t, JHH=6.5 Hz, 3H, CH3); 1.20 (t, JHH=7.0
Hz, 18H, CH3); 1.24 (m, 18H, CH2); 1.44 (m, 2H,
CH2); 1.56 (m, 2H, CH2); 3.83 (q, JHH=7.0 Hz, 12H,
CH2O). 13C-NMR: l 8.09 (CHSi); 14.37 (CH3); 18.53
(CH3); 23.02, 24.29, 29.71, 29.82, 30.01, 30.25, 32.28,
32.56 (CH2); 58.65 (CH2O). 29Si-NMR: l −46.67.
Mass spectrum (30 eV): m/e 463 [M+ −45 (EtOH),
72%]; 163 [(EtO)3Si+, 100%]; 57 (C4H9+, 16%); 45
(EtO+, 3.2%).
1
was obtained as a colorless liquid (0.71 g, 97%). H-
NMR (CDCl3): l 1.24 (t, JHH=7.0 Hz, 18H, CH3);
3.88 (q, JHH=7.0 Hz, 12H, CH2). 13C-NMR: l 1.35
(Si–Cꢀ); 18.35 (CH3); 59.31 (CH2); 167.70 (ꢀCꢀO).
29Si-NMR: l −56.90. IR (CDCl3): 2110 cm−1 (s).
Mass spectrum (70 eV): m/e 366 (M+, 4.2%); 321
[M+ −45 (OEt), 22%]; 294 (100%); 45 (EtO+, 36%).
4.13. Synthesis of chlorotriethoxysilane
4.9. Synthesis of [tris(triethoxysilyl)methyl] lithium salt
To a pentane solution (70 ml) of silicon tetrachloride
(17 g, 0.1 mol) at −70°C, was added dropwise ethanol
(20 ml, 0.34 mol). After being warmed up to r.t., the
solution was stirred overnight. The product was then
purified by distillation (b.p. 90–92°C, 71 mm Hg). A
mixture (15.3 g) was obtained, containing dichlorodi-
ethoxysilane (1%), chlorotriethoxysilane (80%) and te-
traethoxysilane (19%), composition being determined
by GC/MS. Characteristic data for chlorotriethoxysi-
To a THF solution (50 ml) of tris(triethoxysi-
lyl)methane (1.0 g, 2 mmol) at −80°C was added
dropwise the stoichiometric amount of t-BuLi in pen-
tane. After the mixture was stirred for 1 h at −65°C,
the lithium salt was ready to use.
4.10. Synthesis of 1,1,1-tris(triethoxysilyl)ethane
To a solution of [tris(triethoxysilyl)methyl] lithium
salt (2 mmol, 30 ml THF) at −80°C, was added methyl
iodide (6 mmol, 0.85 g). After the solution was warmed
up to r.t. and the solvent evaporated, the residue was
treated with pentane and filtered. The product was then
isolated by distillation (b.p. 106–107°C, 10−2 mm Hg),
1
lane: H-NMR (CDCl3): l 1.25 (t, JHH=7.0 Hz, 9H,
CH3); 3.89 (q, JHH=7.0 Hz, 6H, CH2). 13C-NMR: l
17.92 (CH3); 60.40 (CH2). 29Si-NMR: l −70.26. Mass
spectrum (70 eV): m/e 197 (M+ −1, 27%); 199 (M+
+
1, 11%); 169 (100%); 163 [(EtO)3Si+, 15%]; 45 (EtO+,
27%). Characteristic data for tetraethoxysilane: 1H-
NMR (CDCl3): l 1.23 (t, JHH=7.0 Hz, 12H, CH3);
3.84 (q, JHH=7.0 Hz, 8H, CH2). 13C-NMR: l 18.35
(CH3); 59.42 (CH2). 29Si-NMR: l −81.80. Mass spec-
trum (70 eV): m/e 208 (M+, 9.5%); 193 (M+ −15,
100%); 163 [M+ −45 (OEt), 62%]; 45 (EtO+, 7.1%).
Characteristic data for dichlorodiethoxysilane: Mass
spectrum (70 eV): m/e 187 (M+ −1, 6.2%); 189 (M+
+1, 4.3%); 173 (M+ −15, 100%); 175 [(M+ +2)−15,
65%]; 45 (EtO+, 4.2%).
1
74% yield. H-NMR (CDCl3): l 1.20 (t, JHH=7.0 Hz,
27H, CH3
6 CH2); 1.30 (s, 3H, CH3–C); 3.90 (q, JHH=
7.0 Hz,, 18H, CH2–O). 13C-NMR: l 3.57 (C–Si); 18.50
(C6 H3–CH2 and C6
H3–C); 59.50 (CH2O). 29Si-NMR: l
−50.33. Mass spectrum (70 eV): m/e 471 [M+ −45
(EtO), 100%]; 163 [(EtO)3Si+, 15%]; 45 (EtO+, 100%).
4.11. Synthesis of tris(triethoxysilyl)bromomethane
To a solution of [tris(triethoxysilyl)methyl] lithium
salt (2 mmol, 30 ml THF) at −80°C was added
bromine (3 mmol, 0.48 g). After the solution was
warmed up to r.t. and the solvent was removed, the
residue was treated with pentane and filtered. The
product was then isolated by distillation (b.p. 109–
4.14. Reaction of bis(triethoxysilyl)bromomethane with
methyllithium
To a THF solution (30 ml) of bis(triethoxysi-
lyl)bromomethane (0.84 g, 2 mmol) at −80°C was
added a stoichiometric amount of MeLi in solution in
diethylether. After the solution was warmed up to r.t.
and the solvent removed, the residue was treated with
1
113°C, 10−2 mm Hg), 62% yield. H-NMR (CDCl3): l
1.24 (t, JHH=7.0 Hz, 27H, CH3); 3.97 (q, JHH=7.0
Hz, 18H, CH2). 13C-NMR: l 16.64 (C–Si); 18.36
(CH3); 60.32 (CH2). 29Si-NMR: l −60.16. Mass spec-

R.J.P. Corriu et al. / Journal of Organometallic Chemistry 562 (1998) 79–88
87
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pentane and filtered. After evaporation of the solvent,
1,1-bis(triethoxysilyl)ethane was obtained as a colorless
liquid (0.58 g, 82% yield), identified by GC and NMR
spectroscopy by comparison with an authentic sample
(see above).
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