EPR STUDY OF PARAMAGNETIC RHENIUM(I) COMPLEXES (BPY(CENTER-DOT-))RE(CO)(3)X RELEVANT TO THE MECHANISM OF ELECTROCATALYTIC CO2 REDUCTION

In situ reduction of (bpy)Re(CO)(3)Cl, bpy = 2,2'-bipyridine, at a pla tinum cathode under CO2 atmosphere in acetonitrile or acetone has prod uced a series of distinct EPR spectra which are attributed to (bpy(.-) ) containing species and which invariably reveal the interaction of th e unpaired electron with the metal nuclei (Re-185,Re-187, I = 5/2). Th e EPR investigation of various model complexes (bpy(.-))Re(CO)(3)X, ge nerated by electrochemical reduction under argon of diamagnetic precur sors (bpy)Re(CO)(3)X, X = Cl-, CF3SO3-, CH3O-, H-, tetrahydrofuran, CH 3CN, CO, HCO2-, HCO3- and CH3C(O)(-) has been used to interpret the re sults from the reactions under CO2 atmosphere.