Visible-light driven H₂ reductive elimination unlocks reactivity in polyhydrido niobium iridium clusters

Heterobimetallic complexes have recently attracted considerable attention due to their interesting bonding patterns and reactivity. Here, we report the synthesis and characterization of a series of polyhydrido niobium-iridium heterobimetallic clusters using the Brønsted acidic Cp*IrH₄ reagent. This series of complexes exhibits Ir-Nb intermetallic distances significantly shorter than the sum of atomic radii suggestive of multiple bonding character within the Nb-Ir interaction. When irradiated with visible light above 400 nm, a reductive elimination of dihydrogen occurs, which generates new species with very short Nb-Ir interactions. This photochemical transformation, absent in the Ta-Ir analogues, not only highlights a divergence in group-5 reactivity, but also unlocks substitution reactivity at the remaining dimethylamido ligand, which is inert in the parent complex.