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

We report here the first purely organometallic fac-[Mn (CO) (bis- NHC)Br] complex with unprecedented activity for the selective electrocatalytic reduction of CO to CO, exceeding 100 turnovers with excellent faradaic yields (η ≈95 %) in anhydrous CH CN. Under the same conditions, a maximum turnover frequency (TOF ) of 2100 s 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 TOF value (ca. 320 000 s ) ever reported for a manganese-based catalyst. A Mn tetracarbonyl intermediate was detected under catalytic conditions for the first time.