A Highly Active N-Heterocyclic Carbene Manganese(I) Complex for Selective Electrocatalytic CO2 Reduction to CO

We report here the first purely organometallic fac-[Mn-I(CO)(3)(bis-(NHC)-N-Me)Br] complex with unprecedented activity for the selective electrocatalytic reduction of CO2 to CO, exceeding 100 turnovers with excellent faradaic yields (eta(CO)approximate to 95%) in anhydrous CH3CN. Under the same conditions, a maximum turnover frequency (TOFmax) of 2100s(-1) was measured by cyclic voltammetry, which clearly exceeds the values reported for other manganese-based catalysts. Moreover, the addition of water leads to the highest TOFmax value (ca. 320000s(-1)) ever reported for a manganese-based catalyst. A Mn-I tetracarbonyl intermediate was detected under catalytic conditions for the first time.