Electrocatalytic reduction of carbon dioxide with Mn(terpyridine) carbonyl complexes

Abstract

The behavior of a series of Manganese (Mn) carbonyl compounds with 2,2′:6′,2′′-terpyridine (tpy) in κ²-N,N′ and κ³-N,N′,N′′ coordination modes under electrochemically reducing conditions is reported. In the presence of carbon dioxide (CO₂) and Brønsted acid (phenol), two-electron reduction to carbon monoxide (CO) and water (H₂O) is observed. Based on data obtained from cyclic voltammetry and infrared spectroelectrochemistry, the active state of the catalyst in the proposed mechanism for all cases is [Mn(κ³-N,N′,N′′-tpy)(CO)₂]⁻. Under these conditions, competing decomposition reactions limit the overall Faradaic efficiency. These results suggest the possibility of developing new tridentate ligand frameworks suitable for catalytic systems with Mn carbonyl cores.