Conversion of Dinitrogen and Oxygen to Nitric Oxide Mediated by Triatomic Yttrium Cations: Reversible N–N Bond Switching

The direct coupling of dinitrogen (N2) and oxygen (O2) to produce value-added chemicals such as nitric acid (HNO3) at room temperature is fascinating but quite challenging because of the inertness of N2 molecules. Herein, an interesting reaction pathway is proposed for a direct conversion of N2 and O2 mediated by all-metal Y3+ cations. This reaction pattern begins with the N≡N triple bond cleavage by Y3+ to generate a dinitride cation Y2N2+, and the electrons that lead to N2 activation in this process mainly originate from Y atoms. In the following consecutive reactions with two O2 molecules, the electrons stored in the N atoms are gradually released to reduce O2 through re-formation and re-fracture of the N-N bonds, with concomitant release of two NO molecules. Therefore, the reversible N-N bond switching acts as an efficient electron reservoir to drive the oxidation of the reduced N atoms, leading to the formation of NO molecules. This method of producing NO by direct coupling N2 and O2 molecules, which is the reversible N-N bond switching, may provide a new strategy for the direct synthesis of HNO3, etc.