Synthesis and thermal reactions of a spiro-type cyclotrisilene obtained from the reaction between a disilenide and a base adduct of a bromosilylene

A spiro-type cyclotrisilene was synthesized by the novel Si-Si coupling reaction of a disilenide and a base-adduct of bromosilylene and characterized by a combination of spectroscopic and crystallographic methods. A facile ring-opening isomerization of the cyclotrisilene to a disilenylsilylene has been examined on the basis of the NMR spectra, analysis of the thermal reaction products, and theoretical calculations. A formal double C-H insertion product of a trisilaallene has also been isolated and structurally characterized.