ISSN 1070-3632, Russian Journal of General Chemistry, 2008, Vol. 78, No. 8, pp. 1633–1634. © Pleiades Publishing, Ltd., 2008.
Original Russian Text © S.V. Basenko, M.G. Voronkov, Cao Meihua, I.A. Gebel’, 2008, published in Zhurnal Obshchei Khimii, 2008, Vol. 78, No. 8,
pp. 1398–1399.
LETTERS
TO THE EDITOR
New Method of Tris(trimethylsilyl) Antimonite Preparation
S. V. Basenkoa, M. G. Voronkova, Cao Meihuab, and I. A. Gebel’a
a Favorskii Irkutsk Institute of Chemistry, Siberian Division, Russian Academy of Sciences,
ul. Favorskogo 1, Irkutsk, 664033 Russia
b Jilin Petrochemical Company Research Institute of Petrochina, China
Received March 9, 2008
DOI: 10.1134/S1070363208080306
Tris(trimethylsilyl) antimonite, (Me3SiO)3Sb was
for the first time prepared by the reaction of
trimethylsilanol with triethyl antimonite in 67% yield
[1]. But the strong tendency of trimethylsilanol to take
part in anhydrocondensation resulting in the formation
of hexamethyldisiloxane decreased the preparative
value of this method. The attempts to prepare tris
(trimethylsilyl) antimonite by the reaction of sodium
trimethylsilanolate with the antimony trichloride [2] or
trimethylsilanol with the antimony triacetate [3] failed.
Later tris(trihydrocarbylsilyl) antimonites attracted the
attention of many researchers [4–6] and were used as
precursors of the antimony silicate glass for coatings in
microelectronics [7].
Subsequent reaction with trimethylchlorosilane or
symmetrization leads to tris(trimethylsilyl) antimonite
according to the scheme.
Me3SiOSbCl2 + (Me3SiO)2SbCl
→ (Me3SiO)3Sb + SbCl3.
(2)
Formation of hexamethyldisiloxane may occur
along a side reaction.
6 Me3SiCl + Sb2O3
→ 3Me3SiOSiMe3 + 2 SbCl.
(3)
All the by-products were identified by chro-
matomass spectrometry.
Dimethyldichlorosilane, methyltrichlorosilane, and
also tetrachlorosilane react with Sb2O3 much more
difficultly and only in the presence of such ionizing
solvent as acetonitrile or DMF. Under these conditions
in the case of dimethyldichlorosilane formed per-
methylcyclosiloxanes (Me2SiO)n, n = 3–7.
We have developed a simple and convenient
procedure for preparing tris(trimethylsilyl) antimonite
based on the reaction of trimethylchlorosilane with the
antimony(III) oxide Sb2O3. Reaction of these com-
pounds proceeds in 3.5:1 molar ratio in the absence of
solvents. First of all the unusually mild dissolution of
Sb2O3 in a small excess of trimethylchlorosilane just at
room temperature is observed. Further maintaining of
the reaction mixture at 18–25°C results in the forma-
tion of a crystalline precipitate of the antimony
trichloride. After its removal the distillation of the
reaction mixture afforded tris(trimethylsilyl) anti-
monite in the yield up to 70%.
3Me2SiCl2 + Sb2O3 → 3[Me2SiO] + 2 SbCl3.
(4)
Oligomerization products of the intermediately
generated dimethylsilanone formed according to the
scheme:
n[Me2SiO] → (Me2SiO)n,
n = 3–7.
(5)
Reaction of the antimony(III) oxide with methyl-
trichloro- or tetrachlorosilane gives a complex mixture
of products which at present is under investigation.
The by-products of this reaction are hexa-
methyldisiloxane, bis(trimethylsiloxy)chlorostibine and
(trimethylsiloxy)dichlorostibine. It proves that the reac-
tion proceeds according to the following scheme.
Tris(trimethylsilyl) antimonite, (Me3SiO)3Sb. A
mixture of 8.7 g of antimony(III) oxide and 12.0 g of
trimethylchlorosilane is stirred at room temperature for
1 h. The crystalline precipitate of the antimony
trichloride was filtered off, and the residue distilled in
3 MeSiCl3 + Sb2O3
→ (Me3SiO)SbCl2 + (Me3SiO)2SbCl.
(1)
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