From a Cyclobutadiene Dianion to a Cyclobutadiene: Synthesis and Structural Characterization of Tetrasilyl-Substituted Cyclobutadiene

Abstract

In less than one minute dianion 1 can be oxidized with 1,2-dibromoethane to give pure tetrakis(trimethylsilyl)cyclobutadiene (2, see scheme). The bridged cyclobutadiene derivative 6 was also similarly synthesized and characterized by X-ray crystallography; it exhibits a planar rectangular structure with localized C=C bonds.