Highly Twisted Ladder Oligosilanes Bearing Phenyl and tert‐Butyldimethylsilyl Groups

Two stereoisomers of bicyclic ladder oligosilanes bearing phenyl and tert‐butyldimethylsilyl groups were synthesized, and their structures and electronic properties are compared with previously reported perisopropyl‐substituted analog. These novel ladder oligosilanes have highly twisted structures with the twist angles between the two terminal Si–Si bonds of av. 37.7 and 39.8°. The UV spectra of these compounds show bathochromically shifted absorption maxima with the longest wavelength compared with that of the perisopropyl‐substituted bicyclic ladder oligosilane. The electronic properties of the ladder oligosilanes were analyzed by theoretical calculations.