Photolysis of 1,3-dimesitylhexamethyltrisilane and 1,2-dimesityltetramethyldisilane

Article abstract of DOI:10.1021/om00025a034

Irradiation at 254 nm of solutions containing 1,3-dimesitylhexamethyltrisilane, (MesMe₂-Si)₂SiMe₂, leads to the formation of 1-mesityl-1-methylsilene, MesMeSi=CH₂, in addition to the anticipated dimethylsilylene, Me₂Si:. The coproduct of dimethylsilylene extrusion, 1,2-dimesityltetramethyldisilane, (MesMe₂Si)₂, is itself photolabile, producing high yields of mesityldimethylsilane, MesMe₂SiH, and 1-mesityl-1-methylsilene. Trapping experiments indicate that both molecular elimination and silicon-silicon bond homolysis followed by disproportionation lead to the silene, whose dimerization yields cis- and trans-1,3-dimesityl-1,3-dimethyl-1,3-disilacyclobutanes. Both the cis- and trans-1,3-disilacyclobutanes were structurally characterized by X-ray crystallography. The silene can be trapped by a variety of reagents in high yield.