A. Gupper, K. Hassler
FULL PAPER
cmϪ1 are clearly temperature dependent. Similar effects are
observed for 1,2-dichlorodisilane. As it is impossible to ac-
curately assign the spectra of the conformers without the
help of ab initio calculations of harmonic frequencies, only
approximate descriptions of the modes are given in Table 3
without any reference to individual rotamers.
added dropwise to a suspension of naphthyllithium in toluene
[594.0 mmol; prepared from 1-bromonaphthalene (123.0 g,
594.0 mmol) and n-butyllithithum]. A temperature of Ϫ20 °C was
maintained throughout the procedure. Upon completion, the reac-
tion mixture was refluxed for three hours. The salts were then sep-
arated by filtration and the solvent removed by evaporation in va-
cuo. The liquid residue was fractionated in vacuo. All volatile prod-
ucts up to a temperature of 120 °C (0.01 Torr) were collected. They
comprised a mixture of naphthyltrichlorosilane, pentachloronaph-
thyldisilane and tetrachlorodinaphthyldisilane. The residue that so-
lidified at room temperature was found to be a mixture of 1,1,2-
trichlorotrinaphthyldisilane and 1,2-dichlorotetranaphthyldisilane.
Crystallization from toluene/petroleum ether (1:5) afforded 34.8 g
(38%) of pure trichlorotrinaphthyldisilane. Ϫ C30H21Cl3Si2 (544.0):
calcd. C 66.23, H 3.89; found C 66.45, H 3.86.
Synthesis of 1,1,2-Trinaphthyldisilane: The hydridodisilane was ob-
tained in quantitative yields by standard reduction of the trichloro-
trinaphthyldisilane with LiAlH4 in diethyl ether. After addition of
a solution of lithium aluminum hydride to the solution of the chlor-
odisilane at 0 °C, the reaction mixture was refluxed for several
hours. Subsequently, it was added dropwise to 2 H2SO4 at a tem-
perature of 0 °C. The organic layer was then separated and the
diethyl ether removed in vacuo. The residue was recrystallized from
petroleum ether giving the desired product as colorless crystals. Ϫ
C30H24Si2 (440.7): calcd. C 81.76, H 5.49; found C 81.75, H 5.59.
Figure 3. Raman spectra in the range ν˜ ϭ 100Ϫ1000 cmϪ1 of 1,1,2-
trichlorodisilane at two different temperatures
So far, the rotational isomerism of 1,1,2,2-tetrachlorodi-
silane has been examined by electron diffraction[33] and vari-
Synthesis of 1,2-Dichlorodisilane: 1,2-Dinaphthyldisilane[31] (5.0 g)
able temperature Raman spectroscopy[34] with the result or the equivalent amount of 1,2-dimesityldisilane[35] was placed in
a thick-walled glass tube. A large excess of hydrogen chloride was
then condensed into the tube, which was sealed carefully. The reac-
tion mixture was cooled to Ϫ70 °C for five hours. The glass tube
was then transferred to a vacuum line and the unreacted hydrogen
chloride removed very carefully. 1,2-Dichlorodisilane was then sep-
arated from naphthalene (or mesitylene) by fractional condensa-
tion, as a colorless liquid. The yield was quantitative.
that the gauche conformer is found to be more stable in
both the gas and the liquid phase. Ab initio calculations at
various levels of theory predict the anti rotamer as the low
energy conformer. We will report on detailed investigations
of the rotational isomerism of the title molecules, including
spectra of the deuterated isotopomers as well as electron
diffraction experiments, in a forthcoming publication.
Synthesis of 1,1,2-Trichlorodisilane: In a procedure completely ana-
logous to the synthesis of 1,2-dichlorodisilane, 1,1,2-trichlorodisil-
ane was obtained in quantitative yields from 1,1,2-trinaphthyldisil-
ane and liquid HCl. It was purified by fractional condensation.
Experimental Section
General: Most chlorinated organosilanes are sensitive towards
moisture with the formation of SiϪOϪSi bonds and hydrogen
chloride. Furthermore, hydridochlorosilanes are also sensitive to-
wards oxygen, many of them igniting spontaneously on contact
with air. All manipulations were therefore carried out under an
atmosphere of dry, oxygen-free nitrogen. All solvents were dried by
distillation from potassium prior to use.
Acknowledgments
The authors thank the Austrian Fonds zur Förderung der wissen-
schaftlichen Forschung for financial support (project P-11878-
CHE).
Raman spectra were recorded with a T64000 spectrometer from
Jobin-Yvon, equipped with a triple monochromator. The spectra
were excited with the green line (514 nm) of an Ar laser. The chloro-
disilanes were condensed into 1 mm capillary glass tubes which
were sealed under an inert N2 atmosphere.
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Synthesis of 1,1,2-trichlorotrinaphthyldisilane:
A solution of
hexachlorodisilane (45.0 g, 167.4 mmol) in 100 mL of toluene was
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2010
Eur. J. Inorg. Chem. 2001, 2007Ϫ2011