The complete oxidation of acetonitrile on Ag(110): catalytic oxidation of -CH2CN

The oxidation of -CH2CN intermediates on Ag(110) results in the formation of CO2, NO and H2O produced apparently via surface formate and nitrile groups. With the use of isotopic labeling and temperature-programmed reaction spectroscopy, it has been shown that the formate is formed via attack of the methylene carbon of -CH2CN by adsorbed atomic oxygen. For this transformation a metallacyclic intermediate, CHOCN, is proposed. Several possible routes to this intermediate are suggested, involving either OCH2CN(a) or =CHCN, either of which is subsequently attacked by oxygen at the methylene carbon. The conversion of -CH2CN to the formate occurs by reaction with adsorbed atomic oxygen at least 130 K below the temperature at which -CH2CN itself reacts on the otherwise clean surface. The results obtained in ultra-high vacuum for the stability of -CH2CN in the presence of coadsorbed oxygen atoms successfully predict the stability of -CH2CN in a high pressure oxygen environment.