1, 2, 3-Trisilacyclopent-4-ene generates silylene to give 1, 2-disilacyclobut-3-ene on both photolysis and thermolysis. The silylene arises from either the central or the terminal silicon atom of the ring depending on the nature of substituents on the central silicon atom on photolysis, but the central silicon is ejected as silylene regiospecifically on thermolysis.
