Theoretical study of the mechanism for the sequential N-O and N-N bond cleavage within N₂O adducts of N-heterocyclic carbenes by a vanadium(III) complex

A theoretical study into the reactions of the N₂O adducts of N-heterocyclic carbenes (NHCs) and a V^(III) complex was carried out using DFT calculations. Unlike most transition metal reactions with N₂O that simply release N₂ following O-atom transfer onto the metal centre, this NHC-based system traps the entire N₂O molecule and then cleaves both the N-O and N-N bond in two consecutive reactions. The NHC presence increases the reactivity of N₂O by altering the distribution of electron density away from the O-atom towards the two N-atoms. This electronic redistribution enables V-N binding interactions to form a reactive N,O-donor intermediate species. Our results show that bond breaking with concomitant ligand migration occurs via a concerted process for both the N-O and N-N cleavage reactions.