Theoretical Investigation of Dissociation versus Intramolecular Rearrangements in Aminohydroxymethylene.

Aminohydroxymethylene (H 2 N-C̈-OH) is the simplest aminooxycarbene which is a heteroatom stabilized carbene. This highly reactive molecule was prepared in an Ar matrix in a recent experimental work. Unimolecular reactivity of this astrochemically important molecule was investigated and only fragmentations were identified contrary to the observations of both fragmentations and intramolecular rearrangements in other hydroxycarbenes. These rearrangement reactions form the corresponding imine and carbonyl compounds. In the present work, direct chemical dynamics simulations of unimolecular chemistry of aminohydroxymethylene were performed in the gas phase to study atomic level dissociation mechanisms. Classical trajectories were generated on-the-fly using potentials and gradients computed at the density functional B3LYP/6-31+G* level of electronic structure theory. Simulation results showed that intramolecular rearrangements accompany fragmentations during the unimolecular decay process of aminohydroxymethylene. However, the average lifetime of the intermediate isomers were found to be only few picoseconds which might not have been long enough for detection in the experiments.