Synthesis and electrocatalytic properties of a cobalt(II) complex supported by N,N-dimethylethylenediamino-N,N-bis(2-tert-butyl-4-ethylphenol)

The reaction of N,N-dimethylethylenediamino-N,N-bis(2-tert-butyl-4-ethylphenol) (H2L′) with CoBr2 gives a Co(II) complex [CoL′(NCMe)] 1, whose structure has been determined by X-ray diffraction. Complex 1 can electrocatalyze hydrogen evolution from both acetic acid, with a turnover frequency (TOF) of 43 mol of H2 per mole of catalyst per hour under −1.30 V versus Ag/AgNO3 (in CH3CN), and from buffer (pH 7.0) with a TOF of 851.1 mol of H2 per mole of catalyst per hour under −1.45 V versus Ag/AgCl. The electronic properties of the ligands are found to play a vital role in determining the catalytic activity.