Polycyclic oligosilanes are fascinating silicon compounds because they show interesting properties owing to delocalization of s(Si-Si) electrons over the three-dimensional silicon framework.  Although catenated polycyclic oligosilanes have been predicted by theoretical calculations to show remarkable conjugation between polycyclic oligosilanes cages, they are still unknown.In the present papar, we synthesized new bicyclo[1.1.1]pentasilanes and persila[n]staffanes (bicyclo[1.1.1]pentasilanes catenated to each other at the bridgehead positions).  Although X-ray analysis shows that catenation of the bicyclopentasilane units causes no considerable change in the structural characteristics of each bicyclopentasilane unit, UV-vis spectra showed the remarkable red-shift of the absorption bands with increasing the number of bicyclopentasilane units.  DFT calculations shows that significant conjugations between s(Si(bridgehead)-Si(bridgehead)) orbitals and between s(Si-Si) orbitals of bicyclo[1.1.1]pentasilane cages are responsible for the remarkable red-shift.

Synthesis and structure of persilastaffanes and related silicon compounds

243rd National Meeting (2012)

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