The sequential activation of H and N mediated by the gas-phase ScN clusters: Formation of amido unit.

The activation and hydrogenation of nitrogen are central in industry and in nature. Through a combination of mass spectrometry and quantum chemical calculations, this work reports an interesting result that scandium nitride cations ScN can activate sequentially H and N, and an amido unit (NH) is formed based on density functional theory calculations, which is one of the inevitable intermediates in the N reduction reactions. If the activation step is reversed, i.e., sequential activation of first N and then H, the reactivity decreases dramatically. An association mechanism, prevalent in some homogeneous catalysis and enzymatic mechanisms, is adopted in these gas-phase H and N activation reactions mediated by ScN cations. The mechanistic insights are important to understand the mechanism of the conversion of H and N to NH synthesis under ambient conditions.