Synthesis and structural characterization of a silacycloheptadiene

Abstract

The dilithium salt of tetraphenylbutadiene (1) reacts normally with phenylethynyltrichlorosilane to give 1-chloro-1-phenylethynyl-2,3,4,5-tetraphenylsilole (3), but with vinyltrichlorosilane the unexpected product is the silacycloheptadiene 2, and X-ray crystal structures were obtained for 2 and 3; the seven-membered ring in 2 adopts a boat conformation, and a possible mechanism for the formation of 2 is suggested.