NADH-Type Hydride Storage and Release on a Functional Ligand for Efficient and Selective Hydrogenation Catalysis

Reminiscent to nature's NAD(+)/NADH hydridestorageand transfer system, we demonstrate here that an iridium complex containinga pyridinium ligand, (PYE+)-P-Ir , iscapable of reversibly storing a hydride upon reaction with formate.The hydride in (PYEH)-P-Ir is stable toward airand water, yet it is released in the presence of electrophiles suchas acids or carbonyl compounds. The full reversibility of the hydridestorage provides access to the hydrogenation procedure that is catalyticin (PYEH)-P-Ir, reaching up to 100,000 turnovernumbers and surpassing other related catalysts by several orders ofmagnitude. With deuterated formate, (PYED)-P-Ir allows for selective deuterium isotope labeling without notablescrambling even in the presence of acids, air, and moisture.