Cooperative Transition Metal/Lewis Acid Bond-Activation Reactions by a Bidentate (Boryl)iminomethane Complex: A Significant Metal-Borane Interaction Promoted by a Small Bite-Angle LZ Chelate

The synthesis of a three-coordinate Pt-borane complex featuring a bidentate LZ (boryl)iminomethane (BIM) ligand is reported. Unlike other LZ-type borane ligands featuring a single-donor buttress, the small bite angle enforced by the BIM ligand is shown to promote a significant metal-borane reverse-dative sigma-interaction akin to multiply strapped metalloboratranes. The steric accessibility of the reactive Pt --> B bond fostered by the BIM ligand allows for a rich reactivity profile toward small molecules that exploit metal-borane cooperative effects. The unligated (boryl)iminomethane BIM is also synthetically accessible and functions as a Frustrated Lewis Pair (FLP). The ability of the free BIM to effect bond activation reactions is contrasted with the behavior seen in the corresponding platinum-bound complexes.