Nitrogen fixation and reduction at boron.

Currently, the only compounds known to support fixation and functionalization of dinitrogen (N) under nonmatrix conditions are based on metals. Here we present the observation of N binding and reduction by a nonmetal, specifically a dicoordinate borylene. Depending on the reaction conditions under which potassium graphite is introduced as a reductant, N binding to two borylene units results in either neutral (BN) or dianionic ([BN]) products that can be interconverted by respective exposure to further reductant or to air. The N isotopologues of the neutral and dianionic molecules were prepared with N-labeled dinitrogen, allowing observation of the nitrogen nuclei by N nuclear magnetic resonance spectroscopy. Protonation of the dianionic compound with distilled water furnishes a diradical product with a central hydrazido BNH unit. All three products were characterized spectroscopically and crystallographically.