The quest for the elusive carbodiimide ion HN [dbnd]C [dbnd]NH [rad]+ and its generation from ionized cyanamide by proton-transport catalysis

Abstract

Tandem mass spectrometry based collision experiments and computational chemistry (CBS-QB3/APNO methods) indicate that the elusive carbodiimide ion HN C NH + is a stable species in the gas-phase. The ion is the most stable of the family of CH 2 N 2 + ions and a very high barrier (87 kcal mol −1) separates it from its tautomer ionized cyanamide, H 2N−C N + . The computations also predict that, in the presence of a single H 2O molecule as the catalyst, the cyanamide ion isomerizes into the carbodiimide ion. Experiments on the ion–molecule reaction of H 2N−C N + and H 2O, a reaction of potential interest in astrochemistry, confirm this prediction.