Abstract
The conversion of dimethylamine ((CH3)(2)NH) to methyl isocyanide (CNMe) through a methylaminocarbyne (CNHMe) intermediate on Pt(111) has been studied experimentally with reflection absorption infrared spectroscopy (RAIRS) and theoretically with density functional theory (DFT). (CH3)(2)NH adsorbs molecularly at 85 K through the nitrogen lone pair and dehydrogenates to produce CNHMe at 350 K. Both experimental observations and the results of DFT calculations show that CNHMe is more stable on the surface than either (CH3)(2)NH or CNMe. However, surface CNHMe can be converted to the less stable CNNle via two different pathways. A small amount of CNMe is formed at temperatures above 350 K due to the dehydrogenation of CNHMe accompanied by desorption of H-2, which drives the reaction forward. The second pathway involves the reaction at 85 K with water adsorbed from the background, which leads to a complete conversion of CNHMe to form both on-top and bent-bridge-bonded CNMe. It is assumed that the dehydrogenation of the CNHMe molecules produces hydrated hydronium ions of the general formula ((H2O)(n)H3O)(+), although direct spectroscopic evidence for such species was not obtained.