Transition-Metal Oxos as the Lewis Basic Component of Frustrated Lewis Pairs

The reaction of oxorhenium complexes that incorporate diamidopyridine (DAP) ligands with B­(C6F5)3 results in the formation of classical Lewis acid–base adducts. The adducts effectively catalyze the hydrogenation of a variety of unactivated olefins at 100 °C. Control reactions with these complexes or B­(C6F5)3 alone did not yield any hydrogenated products under these conditions. Mechanistic studies suggest a frustrated Lewis pair is generated between the oxorhenium DAP complexes and B­(C6F5)3, which is effective at olefin hydrogenation. Thus, we demonstrate for the first time that the incorporation of a transition-metal oxo in a frustrated Lewis pair can have a synergistic effect and results in enhanced catalytic activity.