Although reductive cleavage of dinitrogen (N2) to nitride (N3‐) 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. Here, we report that 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 N3‐, evolving NH3. Isotopic labelling experiments confirm 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.