EPR interpretation and electrocatalytic H2 evolution study of bis(3,5-di-methylpyrazol-1-yl)acetate anchored Cu(II) and Mn(II) complexes

•Two Cu(II) and Mn(II) complexes formed by a ‘scorpionate’ ligand are characterized.•EPR study allows getting insight on the magnetic coupling between the metal ions.•EPR indicates an equilibrium between penta- and hexa-coordination in organic solution.•Cu(II) complex is tested as electrocatalyst in the H2 evolution.•High catalytic activity of Cu(II) species suggests an application in water splitting.