PHOTOLYSIS OF TETRAMETHYLSILANE AT 147 NM - REACTIVITY OF (CH3)3SI AND (CH3)2SICH2

Results of the photolysis of tetramethylsilane at 147 nm are reported. The observed products, H2, CH4, C2H6, (CH3)3SiH, and (CH3)6Si2, along with accumulated evidence from additive experiments, suggest the primary processes (CH3)4Si → CH4 + (CH3)2SiCH2, (CH3)4Si → CH3 + H + (CH3)2SiCH2, and (CH3)4Si → CH3 + (CH3)3Si followed by combination, disproportionation, and abstraction reactions of the radical intermediates. The disproportionation/combination ratio for trimethylsilyl radicals is about 0.48. (CH3)3Si abstracts hydrogen from a variety of donors approximately 20 times faster than CH3. Both observations were unexpected based on previous work involving (CH3)3Si. (CH3)2SiCH2 behaves as anticipated based on the previously reported photolysis of 1,1-dimethylsilacyclobutane. © 1979 American Chemical Society.