Pressure and temperature dependence of the gas-phase reaction of silylene with dimethyl ether
Abstract
Gas-phase reaction rate constants for the reaction of silylene, SiH2, with ia the formation of a complex. At the highest temperature studied (441 K), the experimental decay curves do not return to the baseline. This is attributed to the system reaching equilibrium, with SiH2 being produced by dissociation of the complex, and provides direct experimental evidence for the formation of the complex. Analysis of the decay curves provided an experimental determination of the equilibrium constant, Keq, at 441 K. The high-pressure rate constants, obtained by extrapolation of the experimental data using RRKM/master equation modelling, yield the Arrhenius parameters log (A/cm3 molecule−1 s−1) =
− 7.6 ± 0.4 and Ea
= 9.3 ± 2.8 kJ mol−1. The RRKM/master equation modelling gives a well depth for the SiH2–CH3OCH3 complex of 87 kJ mol−1. This compares with a value of 88.4 ± 1.7 kJ mol−1 determined from Keq at 441 K. Ab initio calculations, performed at the MP2/6-311 + G** level of theory, give a well-depth for the complex of 82.9 kJ mol−1, in excellent agreement with this value.