The gas-phase reaction of SiH2 with dimethylether: kinetic evidence for direct formation of a donor–acceptor adduct

The kinetics of the title reaction have been investigated at 296 K (3–400 Torr in Ar and 3–50 Torr in SF6), and between 298 and 434 K (5 Torr in Ar). The second-order rate constants increase by ca.×20 between 3 and 400 Torr (Ar) and ca.×6 between 3 and 50 Torr (SF6). At 5 Torr Ar, an Arrhenius plot gives log(A/cm3 molecule−1 s−1)=−13.71±0.13 and Ea=−15.3±0.9 kJ mol−1. The data are consistent with the formation of an H2Si…OMe2 donor–acceptor adduct. RRKM/master equation modelling of the rate constants at 296 K gives a high pressure limiting value (k∞) of 6.6×10−10 cm3 molecule−1 s−1 and a binding energy of 96 kJ mol−1 for the adduct.