The sequential activation of H 2 and N 2 mediated by the gas-phase Sc 3 N + 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 Sc ₃ N ⁺ can activate sequentially H ₂ and N ₂ , and an amido unit (NH ₂ ) is formed based on density functional theory calculations, which is one of the inevitable intermediates in the N ₂ reduction reactions. If the activation step is reversed, i.e., sequential activation of first N ₂ and then H ₂ , the reactivity decreases dramatically. An association mechanism, prevalent in some homogeneous catalysis and enzymatic mechanisms, is adopted in these gas-phase H ₂ and N ₂ activation reactions mediated by Sc ₃ N ⁺ cations. The mechanistic insights are important to understand the mechanism of the conversion of H ₂ and N ₂ to NH ₃ synthesis under ambient conditions.