A Cobalt Molecular Catalyst for Hydrogen Evolution Reaction with Remarkable Activity in Phosphate Buffered Water Solution

Herein, we show that [Cp*Co(2-ampy)I]I (2-ampy = 2-aminomethyl-pyridine) is an extremely active catalyst for HER, exhib- iting a record TOF of 109000 s-1 in phosphate buffered water solution (pH 7). The key to this remarkable activity stems from the establishment of a network of weak interactions in the second coordination sphere. As a matter of fact, both experimental and theoretical studies strongly suggest that the –NH2 functionality of 2-ampy ligand acts as an anchoring and orienting group for H2PO4- through the establishment of an in- termolecular hydrogen bonding with it that, in turn, intermolecularly donates a proton to Co–H liberating H2.