,1,2,2,3,3,4,4-octamethyltetrasilanylenemethylene) of a highly regulat
ed structure was synthesized by anionic ring opening polymerization of
octamethyltetrasilacyclopentane. In this polymerization process, alph
a-silyl carbanions play an important role. In this polymer, delocaliza
tion in the ground state is much important in the sigma-conjugation be
tween the tetrasilanylene units via the methylene units.