EPR study of paramagnetic rhenium(I) complexes (bpy>>·>>–>>)Re(CO)3X relevant to the mechanism of electrocatalytic CO2 reduction†

Abstract

In situ reduction of (bpy)Re(CO)₃Cl, bpy = 2,2′-bipyridine, at a platinum cathode under CO₂ atmosphere in acetonitrile or acetone has produced a series of distinct EPR spectra which are attributed to (bpy^˙–) containing species and which invariably reveal the interaction of the unpaired electron with the metal nuclei (^185,187Re, I = 5/2). The EPR investigation of various model complexes (bpy^˙–)Re(CO)₃X, generated by electrochemical reduction under argon of diamagnetic precursors (bpy)Re(CO)₃X, X = Cl^–, CF₃SO₃^–, CH₃O^–, H^–, tetrahydrofuran, CH₃CN, CO, HCO₂^–, HCO₃^– and CH₃C(O)^– has been used to interpret the results from the reactions under CO₂ atmosphere.