LASER-GENERATED SILENES AND THEIR GAS-PHASE POLYMERIZATION

Infrared and excimer laser-powered decompositions of silacyclobutanes R(2)SiCH(2)CH(2)CH(2) (R=H, CH3, CH2=CH and HC=C), 4-silaspiro[3,4]oct ane and 4-silaspiro[3,3]heptane in the gas phase are shown to be domin ated by elimination of ethene to yield transient silenes which efficie ntly polymerize into solid polycarbosilane deposits, potential precurs ors to silicon carbide. IR laser powered decomposition of tetramethylc yclotetrasiloxane affords transient hydroxy(methyl)silylene. The organ osilicon transients were identified by chemical trapping experiments. Copyright (C) 1997 Elsevier Science Ltd.