Trichlorosilylation of chlorogermanes and chlorostannanes with HSiCl3/Net3 followed by base-catalysed formation of (Me3Ge)2Si(SiCl3)2 and related branched stannylsilanes

Article abstract of DOI:10.1016/S0022-328X(98)01218-2

Chlorotrimethylgermane 1 and dichlorodimethylgermane 4 react with trichlorosilane and triethylamine to provide trichlorosilylgermanes Me_4-nGe(SiCl₃)_n (n = 1: 2; n = 2: 5) in fair yields, as distillable liquids. The formation of 2 is followed by base-catalysed decomposition reactions leading to novel solid (Me₃Ge)₂Si(SiCl₃)₂ 3. Chlorotrialkylstannanes 6a-c (6a: R = CH₃, 6b: R = C₂H₅, 6c: R = n-C₄H₉) react with trichlorosilane and triethylamine providing the branched silylstannanes (R₃Sn)2Si(SiCl₃)₂ 7a-c and traces of silylstannanes R₃SnSiCl₃ 8a-c. Only 7a was isolated in a pure state. Heating 7a or crude 7b and 7c with benzyl chloride leads to the formation of benzyltrichlorosilane (10). The constitution of compounds 2, 3, 5 and 7a was confirmed by MS, NMR and analytical data. The structures of C₆D₆-solvated 3 and C₆H₆-solvated 7a were determined by X-ray diffraction, and shown to be isotypic.

Full text of DOI:10.1016/S0022-328X(98)01218-2

Journal of Organometallic Chemistry 579 (1999) 156–163
Trichlorosilylation of chlorogermanes and chlorostannanes with
HSiCl3/Net3 followed by base-catalysed formation of
(Me3Ge)2Si(SiCl3)2 and related branched stannylsilanesꢀ
Lars Mu¨ller a, Wolf-Walther du Mont a,*, Frank Ruthe a, Peter G. Jones a,
Heinrich C. Marsmann b
a Institut fu¨r Anorganische und Analytische Chemie der Technischen Uni6ersita¨t, Uni6ersita¨t Braunschweig, Hagenring 30, Postfach 3329,
D-38023 Braunschweig, Germany
b Anorganische und Analytische Chemie, Uni6ersita¨t-Gesamthochschule Paderborn, Warburger Strasse 100, D-33098 Paderborn, Germany
Received 28 October 1998
Abstract
Chlorotrimethylgermane 1 and dichlorodimethylgermane 4 react with trichlorosilane and triethylamine to provide trichlorosi-
lylgermanes Me4−nGe(SiCl3)n (n=1: 2; n=2: 5) in fair yields, as distillable liquids. The formation of 2 is followed by
base-catalysed decomposition reactions leading to novel solid (Me3Ge)2Si(SiCl3)2 3. Chlorotrialkylstannanes 6a–c (6a: R=CH3,
6b: R=C2H5, 6c: R=n-C4H9) react with trichlorosilane and triethylamine providing the branched silylstannanes
(R3Sn)2Si(SiCl3)2 7a–c and traces of silylstannanes R3SnSiCl3 8a–c. Only 7a was isolated in a pure state. Heating 7a or crude 7b
and 7c with benzyl chloride leads to the formation of benzyltrichlorosilane (10). The constitution of compounds 2, 3, 5 and 7a
was confirmed by MS, NMR and analytical data. The structures of C6D6-solvated 3 and C6H6-solvated 7a were determined by
X-ray diffraction, and shown to be isotypic. © 1999 Elsevier Science S.A. All rights reserved.
Keywords: Organotin chlorides; Organogermanium chlorides; Trichlorosilane; Silylgermanes; Silylstannanes; Disproportionation
Recently, the application of the Benkeser reaction to
organophosphorus halides led to an extremely useful
1. Introduction
new trichlorosilylphosphane synthesis [3,4], in addition
to the known route using hexachlorodisilane [5–7].
tance as trifunctional precursors for the synthesis of
Trihalogenosilyl compounds are of general impor-
highly functionalised silicon compounds, such as
branched silicones and silsesquioxanes. Trichlorosilyl-
RCl+HSiCl3+NEt3
stannanes and related germanes, being a kind of a-halo-
gen(metal)silane, would be most desirable precursors
for further transformations. According to Benkeser,
trichlorosilane/triethylamine is a very useful reagent for
the synthesis of organic trichlorosilanes from the re-
lated alkyl or acyl halides [1,2].
“RSiCl3+HNEt3Cl (Refs. [1,2])
R2PCl+HSiCl3+NEt3
(1)
(2)
“R2PSiCl3+HNEt3Cl (Refs. [3,4])
We also found that trichlorosilane/triethylamine even
reacts with chlorotrimethylstannane 6a in a straightfor-
ward way producing a solid trichlorosilyl stannane that
we believed to be Me3SnSiCl3 8a [4]. Similarly,
Me3SiSiCl3 had been reported to be formed by the
reaction of HSiCl3/NEt3 with trimethylsilyl triflate [8].
ꢀ Dedicated to Professor Reinhard Schmutzler on the occasion of
his 65th birthday.
* Corresponding author.
0022-328X/99/$ - see front matter © 1999 Elsevier Science S.A. All rights reserved.
PII: S0022-328X(98)01218-2

L. Mu¨ller et al. / Journal of Organometallic Chemistry 579 (1999) 156–163
157
When we extended this type of reaction to chloro-
trimethylgermane 1, we were surprised that, depending
on the reaction time and the work-up procedure, two
different products—a liquid or a solid—of similar
carbon and hydrogen content could be isolated. This
observation led us to reinvestigate the reaction of chl-
orotrimethylstannane 6a with trichlorosilane/triethyl-
amine and to extend it to other trialkylchlorostannanes
6b and 6c by following the course of the reactions by
119Sn- and 29Si-NMR. In the following we will report
surprising results on the Benkeser reaction applied to
methylchlorogermanes and we will show that, contrary
to our previous report [4], trichlorosilylstannanes
R3SnSiCl3 8a–c have only a short lifetime under the
conditions of the Benkeser reaction. Novel branched
silylstannanes (R3Sn)2Si(SiCl3)2 7a–c are the main prod-
ucts.
stable. Work-up of reaction mixtures from 1 with
HSiCl3/NEt3 after several days by filtration and evapo-
ration of the solvent gave a yellowish waxy solid (ca. 40%
crude yield). After dissolving the residue in C6D6, colour-
less crystals of C6D6-solvated 3 separated from the
solution. Long drying of the crystals at 0.05 mbar led to
3 as an amorphous solid that gave satisfactory analytical
data.
Its molecular ion in the mass spectrum, its elemental
analysis, and its 29Si-NMR spectrum (as well as the
comparison with the related tin compound) suggested
that 3 is (Me3Ge)2Si(SiCl3)2. Final proof was provided by
an X-ray structure determination (see below).
Elemental analyses of several samples of 3 (increased
C, H content) indicate that the removal of solvent
molecules, especially aromatic hydrocarbons, from 3 is
difficult. The C, H content of such samples can be
(deceptively) rather similar to that of 2. Single crystals
of 3 from C6D6 solutions contain one equivalent of C6D6.
2. Results and discussion
Dichlorodimethylgermane
4
reacts with the
trichlorosilane/triethylamine reagent at r.t. in pentane
solution with precipitation of triethylammonium chlo-
ride. Work-up after 10 days stirring provided dimethyl-
bis(trichlorosilyl)germane 5.
2.1. Reactions of Me3GeCl and Me2GeCl2 with
HSiCl3/NEt3
Chlorotrimethylgermane 1 reacts with the trichlorosi-
lane/triethylamine reagent at room temperature (r.t.) in
pentane solution with precipitation of triethylammo-
nium chloride leading to trichlorosilyltrimethylgermane
2 as the main product, which was identified by singlet
Me2GeCl2+2HSiCl3+2NEt3
4
“Me2Ge(SiCl3)2+2HNEt3Cl
(5)
5
Surprisingly, a decomposition reaction of 5, related to
that of 2 to 3 (Eq. (4)), was not observed even when the
work-up procedure was untertaken after several weeks.
Distillation furnished pure 5 in very good yield as a
colourless liquid. Compound 5 gave satisfactory elemen-
tal analyses and displayed its molecular ion by mass
spectroscopy. Compound 5 is thermally stable, but
sensitive to moisture.
The observation that the yield of 2 but not that of 5
was affected by long reaction times, implies that 2
decomposes steadily under the reaction conditions (pres-
ence of NEt3, HNEt3Cl) whereas 5 does not. Experimen-
tal evidence was provided by addition of a small amount
of NEt3 to pure distilled 2 and 5 in NMR tubes. After
2 days at r.t. ca. 50% of 2 was decomposed (formation
of 3, Me3GeCl 1 and SiCl4), whereas 5 was still com-
pletely unchanged.
1
signals in the H-, 13C- and 29Si-NMR spectra of the
reaction mixture.
Me3GeCl+HSiCl3+NEt3“Me3GeSiCl3+HNEt3Cl
1
2
(3)
NEt
4Me3GeSiCl3 “3(Me3Ge)2Si(SiCl3)2+SiCl4
2
3
+2Me3GeCl
(4)
1
However, when the mixture was stirred for several
days, the intensity of the NMR-signals of compound 2
decreased in favour of another set of 1H-, 13C- and
29Si-NMR singlet signals of the novel species 3; some
chlorotrimethylgermane 1 and small amounts of other
unidentified compounds were also present. Species 3
became the main product after several days. The 29Si-
NMR spectra of a more concentrated solution revealed
that the spectrum of the new compound 3 exhibits two
29Si resonances, one at 17 ppm (close to that of com-
pound 2) and a weaker one far upfield at −84 ppm.
Work-up of reaction mixtures from 1 with HSiCl3/NEt3
after moderate reaction time (20 h) by filtration and
evaporation of the solvent and distillation furnished pure
2 in a ca. 50% yield as a colourless liquid. Compound
2 gave satisfactory elemental analyses and displayed its
molecular ion by mass spectroscopy. Its physical data are
different from those previously reported [7]. The pure
compound is moisture-sensitive, but thermally quite
More systematic studies concerning the different be-
haviour of 2 and 5 towards nucleophiles are under way.
Attempted extension of the Benkeser reaction to
MeGeCl3 and GeCl4 was apparently accompanied by
reduction; no single product could be isolated from the
reaction mixtures.
2.2. Reactions of trialkylchlorostannanes with
HSiCl3/NEt3
The reactions of trialkylchlorostannanes R3SnCl (6a:

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L. Mu¨ller et al. / Journal of Organometallic Chemistry 579 (1999) 156–163
R=Me, 6b: R=Et, 6c: R=n-Bu) with the trichlorosi-
lane/triethylamine reagent were monitored by 13C-,
119Sn- and 29Si-NMR. Typically, triethylamine was
added dropwise to mixtures of the chlorostannane with
trichlorosilane.
to a crude liquid mixture of 6c and 7c in pentane and
stirring for another month. Enriched 7c was accompa-
nied by 6c and small amounts of 8c.
In a further experiment, 6c was treated with four
equivalents of the HSiCl3/NEt3 reagent. Under these
conditions, 7c was accompanied by ca. 15% of com-
pound 9c. A 29Si-NMR spectrum of the mixture re-
vealed, that, like 7c (l 29Si= +21 and −107.7 ppm),
9c contains trichlorosilyl groups and a central silicon
atom (l 29Si= +12 and −88.3 ppm). We propose that
9c is n-Bu3SnSi(SiCl3)3.
In additional experiments, we investigated whether
compounds 7a–c could be used as alternative to the
Benkeser-like trichlorosilylation of benzyl chloride with
HSiCl3/NEt3. Decomposing samples containing 7a–c
by heating them with excess benzyl chloride provided
benzyltrichlorosilane (10) accompanied by the tri-
alkylchlorostannanes 6a–c. Following the reactions
with the help of 13C-, 29Si-, and 119Sn-NMR spectra
indicated that heating was required in each case and
that (impure) 7b and 7c reacted faster than 7a.
2.2.1. Reaction of chlorotrimethylstannane 6a with
HSiCl3/NEt3
Within 3 days at r.t. in pentane, ca. 25% of chloro-
trimethylstannane 6a (its 119Sn-NMR resonance in the
reaction mixture, l 119Sn= +117 ppm, indicating co-
ordination with triethylamine) was converted into a
new tin compound 7a that exhibits a l 119Sn signal at
−53 ppm [4,7] and traces of Me3SnSiCl3 8a (l 119Sn=
−70 ppm). To complete the reaction as far as possible,
stirring continued for 2 weeks. After separation of the
solution from the triethylammonium chloride residue,
the crude compound (Me3Sn)2Si(SiCl3)2 (7a) was ob-
tained in a ca. 40% yield. Several days after dissolving
7a in benzene, colourless crystals of benzene-solvated
7a had separated. Removal of benzene at 0.05 mbar
gave 7a as an amorphous colourless solid that gave
satisfactory analytical data. In an EI MS, the molecular
ion of 7a showed the expected, characteristic isotopic
pattern.
(R3Sn)2Si(SiCl3)2+C6H5CH2Cl
7a−c
“C6H5CH2SiCl3+R3SnCl
(8)
10
6a−c
hw
(Me3Sn)2Si(SiCl3)2“
7a−c
Me3SnSiCl3+Me3SnCl+Me2SnCl2
R3SnCl+HSiCl3+NEt3“R3SnSiCl3+HNEt3Cl (6)
(9)
8a−c
6a−c
8a
8a
a: R=Me; b: R=Et, c: R=n-Bu
A first experiment concerning the photochemical
cleavage of compound 7a was also carried out: UV-ir-
radiating a benzene solution (twice 45 min) of 7a led to
50% decomposition. Analysis of the mixture after re-
moval of the solvent by 13C- and 119Sn-NMR and by EI
MS allowed the detection of compounds 6a (ca. 50%
relative to unconsumed 7a (ꢀ100%), from the 119Sn
signal intensity), 8a (ca. 40%) and Me2SnCl2 (ca. 20%).
The persistence of significant amounts of 8a in the
absence of base deserves further interest. Base-catalysed
decomposition is obviously a common feature of com-
pounds Me3MSiCl3 (M=Si [12], Ge, Sn).
NEt
4R3SnSiCl3 “3(R3Sn)2Si(SiCl3)2+SiCl4+2R3SnCl
8a−c
7a−c
(7)
2.2.2. Reaction of chlorotriethylstannane 6b with
HSiCl3/NEt3
Upon addition of triethylamine to Et3SnCl/HSiCl3,
Et3NHCl spontaneously crystallises. However, after 7
days of stirring, a 119Sn-NMR spectrum shows that ca.
50% of 6b is still unconsumed. Within 31 days, ca. 80%
consumption of 6b was confirmed by NMR. In addi-
tion to the signals of starting material 6b and main
product 7b, another small signal at l 119Sn= −59 ppm
assignable to Et3SnSiCl3 8b was also observed. Isola-
tion of pure 7b was not achieved.
2.3. NMR spectra and structure determination
Heteronuclear NMR data of 2, 3, 5 and 7a–c and
observed 119Sn resonances of 8a–c are collected in
Table 1. Compounds 2, 3, 5 and 7a give 1H and
13C-NMR singlets of the CH3 groups, as well as 29Si-
NMR resonances of the SiCl3 groups. The decisive
distinction between compounds 2 and 3 and between 7
and 8/9 can be made on the basis of additional weaker
29Si resonances in the upfield region (3: −84, 7a:
−106.4, 7b: −108.2, 7c: −107.4, 9c: −88.3 ppm).
These resonances are comparable with those of the
central silicon atoms of neopentane-like branched
silanes such as Si(SiCl3)4 [9]. A 29Si-CP-MAS measure-
ment on an amorphous solid sample of 7a indicates
2.2.3. Reaction of chlorotri-n-butylstannane 6c with
HSiCl3/NEt3
At an early stage of the reaction, unconsumed 6c is
accompanied by 7c (l 119Sn= −53 ppm), and traces of
8c (l 119Sn= −71.8 ppm) and a third new compound
9c (l 119Sn= −46.8 ppm). After 4 days, work-up by
removal of Et3NHCl and pentane gave a liquid that still
contained 50% of 6c in addition to the branched silyl-
stannane 7c. Distillation at 106°C/0.1 mbar allowed the
removal of 6c, but attempts to isolate 7c from the
residue failed. Enrichment of 7c up to ca. 85% was
achieved by addition of an excess of HSiCl3 and NEt3

L. Mu¨ller et al. / Journal of Organometallic Chemistry 579 (1999) 156–163
159
Table 1
13C-, 29Si- and 119Sn-NMR shifts of trichlorosilyl derivatives of C, Si, Ge and Sn and reference compounds
1
3
2
9
l
C
l
S
i
l
119Sn
Me3CSiCl3
+24.37 [CH3], +26.14 [CC3]
+17.3
Me3SiSiCl3 [12]
*
+17.5 [SiCl3], −7.2 [SiC3]
Me3GeSiCl3
2
−2.8
+17.8
Me3SnSiCl3 8a
Et3SnSiCl3 8b
−8.6
*
*
*
−70
−59
n-Bu3SnSiCl3 8c
Me3SnSiMe3 [13]
*
*
−71.8
−126.7
+1.13 [CSi], −11.52 [CSn]
−5.8
−11.0
+13.1
Me2Ge(SiCl3)2
Si(SiCl3)4 [9]
5
+3.5 [SiCl3], −80.0 [SiSi4]
+17.2 [SiCl3], −84.2 [Ge2SiSi2]
+19.6 [SiCl3], −106.4 [Sn2SiSi2]
+19 [SiCl3], −112 [Sn2SiSi2]
(Me3Ge)2Si(SiCl3)2
3
+0.8
(Me3Sn)2Si(SiCl3)2 7a −8.0
29Si-CP-MAS-NMR
of 7a
−55.2
(Et3Sn)2Si(SiCl3)2 7b
+3.8 [SnC], +12.1 [SnCC]
+21.0 [SiCl3], −108.2 [Sn2SiSi2]
+21.3 [SiCl3], −107.4 [Sn2SiSi2]
+12.0 [SiCl3], −88.3 [SnSiSi3]
−45.0
−52.7
−46.8
(n-Bu3Sn)2Si(SiCl3)2 7c +12.2 [SnC], +14.0 [SnC3C], +27.8 [SnC2C], +30.3 [SnCC]
n-Bu3SnSi(SiCl3)3 9c
* Not available.
and the trimethystannyl groups within 7a appear to be
slightly more bulky than trichlorosilyl groups. Consis-
tent with this, Cl–Si–Cl angles (106.20–107.08°) of 3
are smaller than C–Ge–C (110.0–111.5°) and Si–Cl
that the same kind of neopentane-related species
(Me3Sn)2Si(SiCl3)2 7a exists in solution and in the solid
state. 119Sn-NMR spectra of compounds 7a–c reveal
that the resonances previously assigned to Me3SnSiCl3
8a [4,7] are in fact those of the branched compound 7a.
Due to insufficient resolution of the corresponding
29Si-NMR spectra, a safe assignment of the 20091 Hz
satellite pair in the 119Sn-NMR spectrum of 7a [J(SnSi)
or J(SnSn), previously assigned to J(SnSi) of 8a) can-
not yet be made [4,7]. In the 29Si-NMR spectrum of 7c,
1J(117, 119Sn, 29Si) was well resolved (92/89 Hz). The
119Sn resonances of compounds 8 appear ca. 14–17
ppm upfield from those of the related branched com-
pounds 7a–c. Satisfactorily resolved 29Si-NMR spectra
of compounds 8a–c were not yet obtained. Similar to
8a, the previous assignments of the 13C- and 29Si-NMR-
data of compound 2 (obtained from R2PGeMe3/Si2Cl6)
were incorrect [7]. At present, the R2PMMe3/Si2Cl6
reaction (M=Ge, Sn) is under reinvestigation. The
mode of decomposition of 2 and 8 and the formation of
3 and of related Si–Sn compounds 7a–c deserves fur-
ther study.
˚
bonds (2.037–2.042 A) are longer than Ge–C bonds
˚
˚
˚
(1.945–1.952 A). Si–Ge (2.394–2.396 A) and Si–Si
(2.307–2.310 A) bond distances are as expected for
comparable compounds with four-coordinated Si and
˚
Ge atoms (Ph3GeSi(SiMe3)3: l(SiGe) 2.415 A, l(SiSi)
˚
˚
2.366 A, [10]; C5Me5(CO)2(Me3P)WSiCl2SiCl3: l(SiSi)
2.350 A, [11]). Analogous to the case of 3, the Cl–Si–
Cl angles (106.11–107.11°) of 7a are smaller than C–
Sn–C (109.8–113.3°) and the Si–Cl bonds
˚
(2.041–2.047 A) are shorter than the Sn–C bonds
˚
˚
˚
(2.126–2.142 A). Si–Sn (2.582–2.583 A) and Si–Si
(2.298–2.306 A) bond distances are as expected. The
benzene molecules occupy regions of the unit cell near
y=0, 0.5, 1,…; they are sandwiched between Me3Sn
and Me3Ge groups, with distances from the Sn/Ge to
˚
the ring centroid of 4.3–4.5 A.
Definitive evidence for the formation of novel
branched compounds 3 and 7a–c is provided by the
structure determination of solid 3 and 7a, which are
isotypic. The molecular structure and a cell plot of 3
solvated with one equivalent of C6D6 are depicted in
Figs. 1 and 2, respectively.
The coordination geometry of the central Si atom of
3 and 7a is slightly distorted tetrahedral. The angles
Ge–Si–Ge of 3 and Sn–Si–Sn of 7a are expanded to
ca. 116° at the expense of BSi–Si–Si (104° for 3 and
105° for 7a), i.e. the trimethylgermyl groups within 3
3. Experimental
All experiments were carried out with exclusion of air
and moisture. Solvents were dried according to stan-
dard procedures. Solution NMR spectra were deter-
mined with Bruker AC 200 instruments (200 MHz for
1H, 50.3 MHz for 13C, 39.8 MHz for 29Si, 74.6 MHz for
119Sn); the 29Si MAS spectrum was run on a Bruker
AMX 300 instrument (59.63 MHz for 29Si, 25° pulse
with 4 s recovery time, rotation: 3000 Hz, resolution: 30
Hz/point); shifts are given relative to TMS (1H, 13C,

160
L. Mu¨ller et al. / Journal of Organometallic Chemistry 579 (1999) 156–163
Fig. 1. Molecular structure of 3. Selected geometric parameters (pm, °): Si(1)–Si(3) 230.98(13), Si(2)–Si(3) 230.74(14), Ge(1)–Si(3) 239.38(10),
Ge(2)–Si(3) 239.62(10) pm; Si(2)–Si(3)–Si(1) 104.23, Ge(1)–Si(3)–Ge(2) 115.83(4), Si(2)–Si(3)–Ge(1) 109.18(5), Si(2)–Si(3)–Ge(2) 108.83°.
29Si) and tetramethylstannane (119Sn)); solvent benzene-
d6.—MS: Finigan Mat 8430.—Elemental analyses:
Carlo Erba analytical gas chromatograph.
tion at 0°C) gave 1.2 g (2.3 mmol) of a yellowish waxy
solid (37% crude yield). This solid was dissolved in 5 ml
of C6D6. From this C6D6 solution, a few colourless
crystals of C6D6-solvated 3 were separated. One of
these crystals was suitable for the X-ray diffraction
study. Prolonged drying of the other crystals at 0.05
mbar led to 3 as an amorphous solid with analytical
purity.
3.1. Synthesis of trimethyl(trichlorosilyl)germane 2
Triethylamine (4.0 g, 40 mmol) was slowly added to
a mixture of 5.5 g (36 mmol) of Me3GeCl 1 and 5.4 g
(40 mmol) of HSiCl3 in 90 ml pentane. Stirring at r.t.
continued for 20 h. Subsequently the solution was
separated from the precipitate and evaporated at 0°C.
Distillation of the brownish residue at 31°C (3.5 mbar)
provided 4.4 g of (48%) 2 as a colourless liquid. After
stirring the reaction mixture for 14 days at r.t., 29Si-
NMR signals of the mixture appeared at l=17.8, 17.2,
−22.3 (silicon grease) and −84.2 ppm. The 29Si signals
at l=17.2 and −84.2 ppm were assigned to 3.
Compound 3: EI MS (70 eV) m/z (%) 532 (6) [M+],
517 (6) [M+ –CH3], 497 (2) [M+ –Cl], 419 (4) [M+
–
CH3, –SiCl2], 295 (8) [M+ –(CH3)2Ge, –SiCl3], 265 (6)
[M+ –Ge(CH3)4, –SiCl3], 245 (3) [M+ –(CH3)3Ge, –
1
SiCl4], base peak 119 [Ge(CH3)3]. H-NMR: l=0.42
ppm (s). 13C-NMR: l= +0.8 ppm (s). 29Si-NMR:
l= +17.2 ppm (s, SiCl3), −84.2 ppm (s, Ge2SiSi2).
C6H18Cl6Ge2Si3 (532.36): Calc. C 13.54, H 3.41, Cl
39.96, Found C 13.75, H 3.46, Cl 38.98%.
Compound 2: EI MS (70 eV) m/z (%) 252 (1) [M+],
237 (16) [M+ –CH3], 217 (4) [M+ –Cl], 139 (60) [M+
–
3.2.1. Structure determination of 3 · C6D6
CH3, –SiCl2], base peak 119 [M+ –SiCl3]. 1H-NMR:
l=0.36 ppm (s). 13C-NMR: l= −2.8 ppm (s). 29Si-
NMR: l=17.8 ppm (s). C3H9Cl3GeSi (252.14): Calc. C
14.29, H 3.60, Cl 42.18, Found C 14.24, H 3.59, Cl
41.99%.
Crystal data: C12H18D6Cl6Ge2Si3, M=616.51, Pbca,
˚
a=12.796(3), b=17.135(3), c=23.211(3) A, V=
5089(2) A , Z=8, Dcalc. =1.609 mg m−3, v=3.130
3
˚
mm−1, T=143 K. A colourless block (0.70×0.50×
0.50 mm) was mounted in inert oil. A total of 6858
intensities were measured (2q 6–55°) using Mo–Ka
radiation on a STOE Stadi-4 diffractometer. After ab-
sorption correction (psi-scans) 5858 unique reflections
(Rint=0.0220) were used for all calculations (program
SHELXL-93; G.M. Sheldrick, University of Go¨ttingen).
The structure was solved by direct methods and refined
anisotropically on F2. H atoms were included using
rigid methyl groups. The final wR(F2) was 0.0912 with
conventional R(F) 0.0379 for 214 parameters.
3.2. Synthesis of bis(trichlorosilyl)bis(trimethylgermyl)-
silane 3
Triethylamine (2.5 g, 25 mmol) was added to a
solution of 1.9 g (12 mmol) of Me3GeCl 1 and 3.4 g (25
mmol) of HSiCl3 in 30 ml pentane. This solution was
stirred at r.t. for another 7 days. Subsequently the
work-up (separation from the precipitate and evapora-

L. Mu¨ller et al. / Journal of Organometallic Chemistry 579 (1999) 156–163
161
Fig. 2. Cell plot of C6D6-solvated 3; C6H6-solvated 7a is isotypic.
3.3. Synthesis of dimethylbis(trichlorosilyl)germane 5
solution. One of these crystals was suitable for a X-ray
diffraction study. Prolonged drying at 0.05 mbar led to
7a as a colourless solid with analytical purity.
To a solution of 13.5 g (0.1 mol) HSiCl3 and 8.7 g (0.05
mol) Me2GeCl2 4 in 120 ml pentane 10.1 g (0.1 mol) of
triethylamine was added, and the mixture was stirred at
r.t. for 10 days. After removal of the precipitate, the
solvent was evaporated under reduced pressure at 0°C.
Distillation of the brown residue at 35°C (0.05 mbar)
provided 14.7 g (79%) of 5 as a colourless viscous liquid.
Compound 5: EI MS (70 eV) m/z (%) 372 (2) [M+],
Compound 7a: EI MS (70 eV) m/z (%) 624 (4) [M+],
base peak 609 [M+ –CH3], 511 (10) [M+ –CH3, –SiCl2],
461 (16) [M+ –2CH3, –SiCl3], 431 (17) [M+ –4CH3,
–SiCl3], 311 (31) [M+ –4CH3, –Sn, –SiCl3], 213 (17)
1
[Me2SnSiCl], 165 (44) [Sn(CH3)3], 135 (22) [SiCl3]. H-
2
2
NMR: l=0.34 ppm (s, J(H, 117Sn)=51.1 Hz, J(H,
119Sn)=53.2 Hz). 13C-NMR: l= −8.0 ppm (s, J(C,
1
357 (4) [M+ –CH3], 337 (5) [M+ –Cl], 257 (18) [M+
–
117Sn)=297 Hz, J(C, 119Sn)=311 Hz. 29Si-NMR (res-
1
SiCl2], 237 (71) [M+ –SiCl3], base peak 135 [M+ –SiCl3,
–SiCl2]. 1H-NMR: l=0.49 ppm (s). 13C-NMR: l=
−5.8 ppm (s). 29Si-NMR: l= +13.1 ppm (s).
C2H6Cl6GeSi2 (371.55): Calc. C 6.47, H 1.63, Cl 57.25,
Found C 6.63, H 1.53, Cl 56.29%.
olution not sufficient to assign satellite signals): l=19.6
ppm (s, SiCl3), −106.4 ppm (s, Sn2SiSi2). 29Si-CP-MAS-
NMR: l=19 ppm (s, SiCl3), −112 ppm (s, Sn2SiSi2).
119Sn-NMR: l= −55.2 ppm (s, two pairs of satellites
resolved: J=199 and 291 Hz). C6H18Cl6Si3Sn2 (624.59):
Calc. C 11.54, H 2.90, Cl 34.06, Found C 11.55, H 2.93,
Cl 33.89%.
3.4. Synthesis of bis(trichlorosilyl)bis(trimethylstannyl)-
silane 7a
3.4.1. Structure determination of 7a · C6H6
Triethylamine (20.2 g, 0.2 mol) was added dropwise to
a mixture of 24.8 g (0.125 mol) of Me3SnCl 6a and 27.0
g (0.2 mol) of HSiCl3 in 320 ml pentane. A small signal
at l 119Sn= −70 ppm (Me3SnSiCl3 8a) was observed
after 3 days stirring at r.t., in addition to the signals of
the main product 7a and the starting material 6a coordi-
nated with NEt3 (l 119Sn=117 ppm). Stirring at r.t.
continued for 14 days to complete the reaction. The
brownish mixture was separated from the precipitate by
filtration (using 2–3 cm Celite® 545 (Merck)) several
times until no further triethylammonium chloride was
detectable; the solvent was evaporated off at 0°C (crude
yield 43%). This brown crude product was dissolved in
120 ml of benzene. After several days, 3.6 g (6 mmol, 10%
yield) of colourless crystals of 7a had separated from this
Crystal data: C12H24Cl6Si3Sn2, M=702.66, Pbca, a=
˚
13.022(2), b=17.412(2), c=23.463(3) A, V=5320.2(12)
A , Z=8, Dcalc. =1.755 mg m−3, v=2.612 mm−1
,
3
˚
T=173 K. A colourless block (0.80×0.40×0.40 mm)
was mounted in inert oil. A total of 4589 intensities were
measured (2q 6–50°) using Mo–Ka radiation on a
Siemens P4 diffractometer. After absorption correction
(psi-scans) 4586 unique reflections were used for all
calculations (program SHELXL-93; G.M. Sheldrick, Uni-
versity of Go¨ttingen). The structure was solved by direct
methods and refined anisotropically on F2. H atoms were
included using rigid methyl groups. The final wR(F2) was
0.0715 with conventional R(F) 0.0301 for 208 parame-
ters.

162
L. Mu¨ller et al. / Journal of Organometallic Chemistry 579 (1999) 156–163
1
1
1
3.5. Reaction of chlorotriethylstannane 6b with
HSiCl3/NEt3
ppm (s, J(Si, Si)=61 Hz, J(Si, 117Sn)=89 Hz, J(Si,
119Sn)=92 Hz, Sn2SiSi2). 119Sn-NMR: l= −52.7 ppm
(s, five pairs of satellites resolved: ca. 308 Hz (weak,
broad), ca. 287 Hz (weak, broad), 93 Hz [1J(Si, 119Sn)],
67.5 Hz (the strongest satellite signals), 21.5 Hz.
To a solution of 12.7 g (53 mmol) Et3SnCl 6b and
13.5 g (100 mmol) of HSiCl3 in 120 ml pentane 10.1 g
(100 mmol) of triethylamine was slowly added. The
immediate formation of triethylammonium chloride
could be observed. A 119Sn-NMR spectrum showed
after 7 days of stirring at r.t. that ca. 50% of the
starting material 6b was still unconsumed. Subsequently
the reaction mixture was stirred for another 24 days at
r.t. The work-up by removing the Et3NHCl and pen-
tane at 0°C gave a dark brown, viscous liquid, which
was very air- and moisture-sensitive. 13C-, 29Si- and
119Sn-NMR spectra indicated ca. 80% consumption of
6b and formation of bis(trichlorosilyl)bis(triethyl-
stannyl)silane 7b. The 119Sn-NMR spectrum also
showed a small signal for Et3SnSiCl3 8b at l 119Sn= −
59 ppm. Isolation of pure 7b by distillation could not
be achieved, because thermal decomposition of 7b led
to 6b.
3.7. Reactions of 7a, 7b and 7c with PhCH2Cl
3.7.1. Reaction of (Me3Sn)2Si(SiCl3)2 7a with
PhCH2Cl
(Me3Sn)2Si(SiCl3)2 7a (400 mg, 0.64 mmol) was dis-
solved in 5 ml benzene. PhCH2Cl (200 mg, 1.5 mmol)
was added to this mixture at r.t. The reaction mixture
was refluxed for 26 h. 13C- and 119Sn-NMR examina-
tions of the yellowish solution indicated the complete
decomposition of 7a and some formation of Me3SnCl
6a (l 119Sn=161 ppm) and 10 (l 13C=32.6 ppm (s,
PhCH2SiCl3), 126.7 ppm (s, p-C), 128.9 ppm (s, m-C),
129.4 ppm (s, o-C), 132.1 ppm (s, ipso-C)).
3.7.2. Reaction of (Et3Sn)2Si(SiCl3)2 7b with PhCH2Cl
PhCH2Cl (1.46 g, 11.5 mmol) was added to 3.9 g (5.5
mmol) of (Et3Sn)2Si(SiCl3)2 7b. The yellow mixture was
refluxed for 2 h. A 119Sn-NMR spectrum showed the
complete decomposition of 7b and the formation of
Et3SnCl 6b. Distillation of the red–orange reaction
mixture furnished 0.8 g (3.5 mmol, 32% yield) of 10
(45°C, 0.5 mbar) and 2.2 g (9.1 mmol, 83% yield) of
Et3SnCl 6b (65°C, 0.5 mbar).
Compound 7b: 13C-NMR: l=3.8 ppm (s, 1J(C,
Sn)=296 Hz, Sn–CH2–CH3), 12.1 ppm (s, Sn–CH2–
1
CH3). 29Si-NMR: l=21.0 ppm (s, J(Si, Si)=62 Hz,
SiCl3), −108.2 ppm (s, 1J(Si, Si)=63 Hz, further
broad satellites J=ca. 86 Hz, Sn2SiSi2). 119Sn-NMR:
l= −45 ppm (s, two pairs of satellites resolved: J=
ca. 75 Hz (broad), and J=308 Hz).
3.6. Reaction of chlorotri-n-butylstannane 6c with
HSiCl3/NEt3
3.7.3. Reaction of (n-Bu3Sn)2Si(SiCl3)2 7c with
PhCH2Cl
Triethylamine (6.1 g, 60 mmol) was added dropwise
to a solution of 18.0 g (55 mmol) of n-Bu3SnCl 6c and
8.1 g (60 mmol) of HSiCl3 in 130 ml pentane. Work-up
after 4 days led to a yellowish, viscous liquid. 13C- and
119Sn-NMR spectra indicated the presence of 7c, uncon-
sumed 6c (50%) and a small amount of n-Bu3SnSiCl3 8c
(l 119Sn= −71.8 ppm). Attempted distillation of 7c led
to thermal decomposition and compound 6c (b.p.
106°C/0.1 mbar) was recovered. The liquid was there-
fore dissolved in 200 ml pentane and stirred for 14 days
at r.t. Subsequently another 8.1 g (60 mmol) of HSiCl3
and 6.1 g (60 mmol) of triethylamine were added to this
yellow solution, which was stirred at r.t. for another 29
days to complete the reaction. Work-up in the same
way led to a dark brown, oily liquid that was very
sensitive to air and moisture. Enrichment of 7c was
possible up to 85%.
PhCH2Cl (1.0 g, 7.8 mmol) was treated with 3.3 g
(3.8 mmol) of (n-Bu3Sn)2Si(SiCl3)2 7c. The yellowish
mixture was heated for 10 h at 100°C. 13C-, 29Si- and
119Sn-NMR spectra of the dark yellow reaction mixture
proved the complete decomposition of 7c and forma-
tion of n-Bu3SnCl 6c (l 119Sn=147 ppm) and 10 (l
29Si=7.8 ppm).
3.8. Photochemical clea6age of 7a
(Me3Sn)2Si(SiCl3)2 7a (320 mg, 0.5 mmol) was dis-
solved in 100 ml benzene. UV-irradiation (150 W) of
the benzene solution for two periods of 45 min and
subsequently removal of the benzene led to a brown
residue that was dissolved in C6D6. About 50% decom-
position of 7a was indicated by a 119Sn-NMR spectrum
of this brown solution. The following signals were
detected after UV-irradiation:
Compound 7c: 13C-NMR: l=12.2 ppm (s, 1J(C,
117Sn)=284 Hz, 1J(C, 119Sn)=296 Hz, Sn–CH2–
(CH2)2–CH3), 14.0 ppm (s, Sn–(CH2)3–CH3), 27.8
(Me3Sn)2
l
119Sn=−54 ppm (intensity: 100), l
13C=−8.1 ppm
3
ppm (s, J(C, Sn) satellites overlapped by the signals of
2
n-Bu3SnCl, Sn–(CH2)2–CH2–CH3), 30.3 ppm (s, J(C,
Si(SiCl3)2 7a:
Me3SnSiCl3
8a:
Sn)=20.5 Hz, Sn–CH2–CH2–CH2–CH3). 29Si-NMR:
l=21.3 ppm (s, 1J(Si, Si)=61 Hz, SiCl3), −107.4
l
119Sn=−70 ppm (intensity: 42), l
13C=−8.6 ppm

L. Mu¨ller et al. / Journal of Organometallic Chemistry 579 (1999) 156–163
163
Me3SnCl 6a: l 119Sn=+162 ppm (intensity: 50), l
References
13C=−1.7 ppm
119Sn=+140 ppm (intensity: 17), l
13C=+1.4 ppm
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Acknowledgements
We thank the Deutsche Forschungsgemeinschaft and
the Fonds der Chemischen Industrie for financial sup-
port.
.