Investigations of tri-t-butyl tin hydride complexes of transition metals in small molecule activation and catalysis

Transition metal complexes containing the sterically encumbered SnBu^t₃ group are the focus of this brief review. The ability of tin compounds to modify both heterogeneous and homogeneous catalysts has been known for some time. Our recent efforts center on utilizing the reagent Bu^t₃SnH to investigate the influence of this ligand, which combines a steric profile similar to that of PBu^t₃, with functional reactivity at the Sn-H bond. These properties of the SnBu^t₃ ligand allow preparation of new complexes and comparison of their structures and reactivities with less encumbered trialkyl stannanes. This has allowed fine-tuning of the strained molecular geometry at the coordinatively unsaturated site and study of how that influences small molecule activation. Reversible H₂ binding and activation, H₂–D₂ scrambling to form HD, C-H activation of bound ligands and solvents, catalytic hydrogenation, and catalytic hydrostannylation have all been observed for select complexes. In addition, a range of metal cluster complexes incorporating stannane moieties have been prepared and structurally characterized. The Bu^t₃SnH ligand provides a new dimension for preparation of new molecular architectures with potential applications in homogeneous and heterogeneous catalysis.