Kinetics of dichlorosilylene trapping by methane and mechanism and kinetics of the methyldichlorosilane decomposition

Article abstract of DOI:10.1002/(SICI)1097-4601(1998)30:1<89::AID-KIN10>3.0.CO;2-G

Data relative to methane trapping of SiCl₂ and a rate constant for the SiCl₂ into C-H bond insertion process of k_-1 = 13.4 M^-1s^-1 at 921 K are reported. Results on the decomposition of the trapping product, methyldichlorosilane, are also reported. This decomposition follows first-order kinetics with a rate constant of k = 1.5±0.2×10^-3 s^-1 at 905 K and produces methane, trichlorosilane, methyltrichlorosilane, and tetrachlorosilane. It is argued that the decomposition involves silylene intermediates, is nonchain, and is initiated primarily by the molecular methane elimination process MeSiHCl₂-1→CH₄+SiCl₂. Free radicals and Si-C bond fission may also contribute to the decomposition but are not dominant. The kinetics of MeSiHCl₂ decomposition are shown to be consistent with the kinetics of the reverse SiCl₂/CH₄ trapping reaction and with the overall reaction thermochemistry. Reaction modeling gives product yields, reactant conversions, and rates in reasonable agreement with the data.