Synergistic Cu Catalysts for Formic Acid Dehydrogenation.

Hexanuclear copper hydride complexes, Cu(μ-H)( meso-L)(RNC) (R = Bu (6a), Cy (6b)), were prepared by using a new linear tetraphosphine, meso-PhPCHP(Ph)(CH)P(Ph)CHPPh ( meso-L), and were converted into active catalysts of [Cu(μ-OCH)( meso-L)(RNC)] under the reaction conditions of formic acid dehydrogenation, where unsymmetric dinuclear copper sites supported by the tetradentate phosphine and isocyanide ligands were essential to demonstrate effective catalytic activity.