Electrocatalytic Reduction of CO2 Using the Complexes [Re(bpy)(CO)3L]n (n = +1, L = P(OEt)3, CH3CN; n = 0, L = Cl-, Otf-; bpy = 2,2‘-Bipyridine; Otf- = CF3SO3) as Catalyst Precursors: Infrared Spectroelectrochemical Investigation

Abstract

This article describes the results of an IR spectroelectrochemical study of the electrocatalytic reduction of carbon dioxide using the complexes [Re(CO)3(bpy)L]n (bpy = 2,2‘-bipyridine; n = 0, L = Cl-, CF3SO3-; n = +1, L = CH3CN, P(OEt)3) as catalyst precursors. The study was performed for the first time with an optically transparent thin-layer electrochemical (OTTLE) cell. The results confirm unambiguously the catalytic activity of the reduced five-coordinate complexes, the radical [Re(CO)3(bpy)]• and the anion [Re(CO)3(bpy)]-. The catalytic behavior of these species could be investigated separately for the first time due to the application of complexes other than those with L = halide, whose catalytic routes may involve simultaneously both radical and anionic catalysis depending on the solvent used. The complex [Re(CO)3(bpy)Cl], so far the most studied catalyst precursor, upon one-electron reduction gives the corresponding radical-anion [Re(CO)3(bpy)Cl]•-, which was previously believed to react directly...