A gas-phase kinetic study of the reaction of silylene with germane: absolute rate constants, temperature dependence and mechanism

Time-resolved studies of silylene, SiH2, generated by laser dash photolysis of phenylsilane, have been carried out to obtain rate constants for its bi molecular reaction with monogermane, GeH4. The reaction was studied in the gas-phase at 10 Torr total pressure in SF6 bath gas, at five temperatures i n the range 295-553 K. The second order rate constants fitted the Arrhenius equation: log(k(3)/cm(3) molecule(-1) s(-1)) = (-9.88 +/- 0.02) + (2.13 +/ - 0.17 kJ mol(-1))/RTln10. Experiments at other pressures showed that these rate constants were unaffected by pressure. The data are consistent with a fast association process occuring (at 298 K) dose to the collision rate. A lthough the probable initial product is silylgermane, H3SiGeH3, thermochemi cal considerations show that this will decompose to GeH2 + SiH4 under exper imental conditions. This silylene insertion process is compared to others a s well as to the insertion processes of methylene, CH2 and germylene, GeH2.