C-H AND C-C BOND ACTIVATIONS BY SILICON - THERMOCHEMISTRY AND MECHANISM OF THE REACTION OF SI+(2P) WITH ETHANE

The reaction of ground-state silicon ion with ethane (-d0, -1,1,1-d3, and -d6) is investigated by using guided ion beam techniques. Absolute reaction cross sections for all product ions are determined as a function of the relative collision energy. At thermal energies, Si+-CH3 accounts for 90% of all products. Exothermic dehydrogenation to form SiC2H4+ and demethanation to form SiCH2+ are observed, but these processes are inefficient. When CH3CD3 is employed as the reactant neutral, all products are observed to incorporate hydrogen and deuterium atoms in near-statistical distributions at low energies. This suggests that the primary HSi+-CH2CD3, CH3CD2-SiD+, and CH3-Si+-CD3 intermediates are rapidly interconverted via a cyclic HDSi(CH2CD2)+ intermediate.