Skeleton–side-group interaction in organopolysilane

The skeleton–side-group interaction due to σ-π mixing in organopolysilane —(SiXY${)}_n$— where X and Y are methyl (Me) and phenyl (Φ) groups, has been theoretically investigated. The results are discussed on the basis of uv photoemission experiments. The σ-π interaction at the valence-band edge produces not only the delocalized σ states along the Si skeleton, but also the localized π states in the individual Φ side groups. On the other hand, the ${\sigma }^{\mathrm{*}}$-${\pi }^{\mathrm{*}}$ interaction at the conduction-band edge is inhibited owing to the orbital symmetry. This paper also presents the results of theoretical investigations on the influence of side-group substitution and of Φ–side-group rotation on the electron distribution along the Si skeleton.