Direct Conversion of N 2 and O 2 to Nitric Oxide at Room Temperature Initiated by Double Aromaticity in the Y 2 BO + Cation.

The conversion of dinitrogen to more useful and reactive molecules has been the focus of intense research by chemists. In contrast to reductive N ₂ fixation, direct oxidation of N ₂ by O ₂ to nitric oxide under mild conditions via a thermochemical process is extremely challenging. Herein, we report the first example of N ₂ and O ₂ activation and coupling under thermochemical conditions through the remarkable ability of Y ₂ BO ⁺ to react with one N ₂ and two O ₂ molecules. Detailed mechanistic studies using mass spectrometry and quantum chemical calculations revealed that the N ₂ activation by Y ₂ BO ⁺ is facilitated by the double aromatic character of the Y ₂ BON ₂ ⁺ intermediate. Subsequent oxidation with O ₂ releases NO in a dearomatization process driven by the formation of stronger Y-O bonds over the Y-N bonds. Our findings represent the first example of N ₂ and O ₂ activation and coupling under thermochemical conditions at room temperature, providing a novel strategy for small-molecule activation.