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 N<small>₂</small>O adducts of <em>N</em>-heterocyclic carbenes (NHCs) and a V<small>^(III)</small> complex was carried out using DFT calculations. Unlike most transition metal reactions with N<small>₂</small>O that simply release N<small>₂</small> following O-atom transfer onto the metal centre, this NHC-based system traps the entire N<small>₂</small>O molecule and then cleaves both the N–O and N–N bond in two consecutive reactions. The NHC presence increases the reactivity of N<small>₂</small>O 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 <em>via</em> a concerted process for both the N–O and N–N cleavage reactions.