Catalytic hydrogenation enabled by ligand-based storage of hydrogen

Biology employs exquisite control over proton, electron, H-atom, or H 2 transfer. Similar control in synthetic systems has the potential to facilitate efficient and selective catalysis. Here we report a dihydrazonopyrrole Ni complex where an H 2 equivalent can be stored on the ligand periphery without metal-based redox changes and can be leveraged for catalytic hydrogenations. Kinetic and computational analysis suggests ligand hydrogenation proceeds by H 2 association followed by H-H scission. This complex is an unusual example where a synthetic system can mimic biology's ability to mediate H 2 transfer via secondary coordination sphere-based processes.