On the Remarkable Role of the Nitrogen Ligand in the Gas‐Phase Redox Reaction of the N2O/CO Couple Catalyzed by [NbN]+.

The thermal gas‐phase catalytic reduction of N2O 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)2]+ systems, in which the oxidation of [Nb]+ and [NbO]+ with N2O is facile, but in which neither [NbO]+ nor [Nb(O)2]+ 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. A matter of spin: The [NbN]+/[ONbN]+ system catalyzes the oxidation of CO through N2O. In contrast, in the [Nb]+/[NbO]+ and [NbO]+/[Nb(O)2]+ systems, [Nb]+ and [NbO]+ are oxidized by N2O, even though neither [NbO]+ nor [Nb(O)2]+ react with CO at room temperature. The origins of the distinctly different reactivities are addressed by quantum chemical calculations. [ABSTRACT FROM AUTHOR]