Electronic structure of polybicyclo[1.1.1]pentasilane, polybicyclo[2.2.2]octasilane, polyoctasilacubane and related compounds

Abstract

Electronic structures in the optimized geometries of polybicyclo[1.1.1]pentasilane, polybicyclo[2.2.2]octasilane, polyoctasilacubane and related compounds are studied theoretically on the basis of the one-dimensional tight-binding self-consistent-field crystal orbital (SCF-CO) method. These silicon-based polymers have rigid-rod-like structures with silicon cages in the main chain skeleton. Results show that the present polysilanes have smaller bandgap values which are similar to those of the ladder polysilanes. It is assumed that the larger delocalization of skeleton σ-electrons is caused by the silicon cages in these polymers.