Synthesis, characterization, structural, redox and electrocatalytic proton reduction properties of cobalt polypyridyl complexes

Two mononuclear Co(III) complexes [Co(bpaq)Cl]Cl: 1 and [Co(bpaq)(OH2)](ClO4)2: 2, bpaqH: (2-(bis(pyridin-2-ylmethyl)amino)-N-(quinolin-8-yl)acetamide) served as electrocatalysts for proton reduction in acetonitrile with acetic acid as an external proton source with overpotentials of 0.412 V for 1 and 0.394 V for 2. Both complexes were fully characterized and further structurally identified by single-crystal X-ray diffraction. Spectral and redox properties for both complexes were investigated along with free ligand. The electrochemical and spectral studies revealed both complexes are stable enough in the acetonitrile/acetic acid mixture.