Electrochemical-driven water reduction catalyzed by a water soluble cobalt(III) complex with Schiff base ligand

A new molecular catalyst based on cobalt complex [LCoCl] (1) is formed by the reaction of N, N-dimethylethylenediamino-N, N-bis(2,4-dimethyl) phenol (H2L) with CoCl2 center dot 6H(2)O for electrolytic water reduction. To our knowledge 1 is by far the most active electrocatalyst for hydrogen generation from water with a turnover frequency (TOF) of 2744 mol of hydrogen per mole of catalyst per hour at an overpotential of -638 mV (pH 7.0). This is attributed to the ionic ligand, L-2, that coordinates strongly through two nitrogen atoms and two oxygen atoms to the cobalt center, leaving one Cl- ion in axial position and making the Cl- ion ionize in water. (C) 2015 Elsevier Ltd. All rights reserved.