Compounds of Persilyl-Substituted π-Electron Systems

Abstract

Recent works on compounds of persilyl-substituted π-electron systems are summarized and reviewed. π-Electron systems include. acetyl, ene, ethylene, allene, butatriene, trimethylenemethane, methylenecyclopropene, cyGlobutadiene, fulvene, benzene, and benzene valence isomers. Some transition-metal complexes of these compounds are included as well.
Since silyl groups perturb π-electron systenis strongly by both steric and electronic effect, these compounds exhibit qui, te unusual and interesting physical and chemical properties. For example, tetrakis(trimethylsilyl)ethylene and hexakis(trimethylsilyl)benzene show reversible thermochromism. The latter undergoes facile valence isomerism to the corresponding Dewar benzene and prismane. Facile transition-metal complex-induced 1, 2-silyl shift is also notable for bissily-substituted acetylene systems. As a result, novel transition-metal complexes of fulvene, trimethylenemethane, and methylenecyclopropene were obtained. The latter has been unprecedented so far. X-Ray crystallographic analyses of these compounds revealed interesting features on the structures.