M. Kako et Y. Nakadaira, Photo-induced electron-transfer reactions of cyclic organosilanes and related compounds, B CHEM S J, 73(11), 2000, pp. 2403-2422
Under photo-induced ET conditions in the presence of CCl4 and BF4-, a Si-Si
sigma -bond readily undergoes chlorinative and fluorinative cleavage, and
gives the corresponding chloro- and fluoro-silanes in good yields. In contr
ast co-photolysis of an aromatic nitrile with a disilane and a tetraalkyl g
roup 14 metal effects selective silylation and alkylation of the nucleus at
the position where spin density is high on its radical anion. Chlorination
with CCl4 and the intra-molecular trap with the hydroxy group have clarifi
ed the radical cationic nature of the intermediate in the photo-induced ele
ctron transfer reactions of organooligosilanes. On the other hand, on photo
-induced electron transfer, 7-silabicyclo[2.2.1]heptadiene derivatives unde
rgo skeletal rearrangement to give 2-silabicyclo[3.2.0]heptadiene and 1-sil
abicyclo[2.2.1]heptadiene derivatives which are also the products from the
direct photolysis. 7,8-Disilabicyclo[2.2.2]octadiene derivatives afford 1,2
-dimethoxydisilane and 1,2-difluorodisilane, respectively on photo-induced
electron transfer in the presence of methanol and BF4-. 1, 2-Disilacyclohex
adiene derivatives undergo ring contraction to give the corresponding silac
yclopentadienes under photoinduced electron transfer conditions. Structural
and electronic characteristics of the radical cation derived from these cy
clic unsaturated organosilanes by MO calculations have been discussed.