Photocatalytic Hydrogenation of an N2‑Derived ReV Imido Complex

Direct hydrogenation of N2 at ambient conditions lags behind the recent advances in molecular N2 (electro-)­fixation. In fact, molecular platforms that couple N2 and H2 activation remain rare. Inspired by recent photocatalytic approaches, we report here the photochemical hydrogenation of an N2-derived rhenium­(V) benzoylimido complex. Self-sensitized photolysis with sacrificial 1,4-cyclohexadiene gave benzamide in a high yield. In turn, a new iridium­(III) porphyrinato hydrido photocatalyst allowed for quantitative photohydrogenation via light-driven net hydride transfer. Transient absorption spectroscopy and computations support a light-driven, stepwise hydride transfer mechanism that is enabled by relativistic effects. This approach provides a new strategy for the reductive transformation of N2 into nitrogenous products beyond ammonia.