Mn-NHC Electrocatalysts: Increasing pi Acidity Lowers the Reduction Potential and Increases the Turnover Frequency for CO2 Reduction

摘要

A new manganese(I) N-heterocyclic carbene electrocatalyst containing:a benzimidazole-pyrimidine-based ligand is reported for the two-electron conversion of CO2. The increased pi acidity of pyrimidine shifts the two-electron reduction to -1.77 V vs Fc/Fc(+), 70 mV more positive than that, for MnBr(2,2'-bipyridine)-(CO)(3); increased catalytic current enhancement is also observed (5.2X vs 2.1X). Theoretical analyses suggest that this heightened activity may follow from the reference for a reduction-first dehydroxylation mechanism.