Synthesis, characterization, and photoreactions of 1,2-disiladigermacyclobutane

A new four-membered ring compound having a Si₂Ge₂ skeleton, octaisopropyl-1,2-disiladigermacyclobutane (1), was synthesized by the reductive coupling of tetraisopropyl-1,2-dichlorosilagermane with sodium in toluene. The structure of 1, which has one Ge-Ge bond, one Si-Si bond, and two Ge-Si bonds in a ring; was confirmed by chemical derivatization; the reactions of 1 with m-chloroperoxy-benzoic acid and PCl₅ led to the selective cleavage of the Ge-Ge bond in 1. The selective extrusion of a germylene from 1 was observed at the initial stage of the photolysis using 254 nm light.