Bimetallic Cooperative Cleavage of Dinitrogen to Nitride and Tandem Frustrated Lewis Pair Hydrogenation to Ammonia

Although reductive cleavage of dinitrogen (N₂) to nitride (N^3?) and hydrogenation with dihydrogen (H₂) to yield ammonia (NH₃) is accomplished in heterogeneous Haber–Bosch industrial processes on a vast scale, sequentially coupling these elementary reactions together with a single metal complex remains a major challenge for homogeneous molecular complexes. Herein, we report that the reaction of a chloro titanium triamidoamine complex with magnesium effects complete reductive cleavage of N₂ to give a dinitride dititanium dimagnesium ditriamidoamine complex. Tandem H₂ splitting by a phosphine–borane frustrated Lewis pair (FLP) shuttles H atoms to the N^3?, evolving NH₃. Isotope labelling experiments confirmed N₂ and H₂ fixation. Though not yet catalytic, these results give unprecedented insight into coupling N₂ and H₂ cleavage and N?H bond formation steps together, highlight the importance of heterobimetallic cooperativity in N₂ activation, and establish FLPs in NH₃ synthesis.