On the Remarkable Role of the Nitrogen Ligand in the Gas-Phase Redox Reaction of the N O/CO Couple Catalyzed by [NbN].

The thermal gas-phase catalytic reduction of N O by CO, mediated by the transition-metal nitride cluster ion [NbN] , has been explored by using FT-ICR mass spectrometry and complemented by high-level quantum chemical calculations. In contrast to the [Nb] /[NbO] and [NbO] /[Nb(O) ] systems, in which the oxidation of [Nb] and [NbO] with N O is facile, but in which neither [NbO] nor [Nb(O) ] react with CO at room temperature, the [NbN] /[ONbN] system at ambient temperature mediates the catalytic oxidation of CO. The origins of the distinctly different reactivities upon nitrogen ligation are addressed by quantum chemical calculations.