Electrochemical and photochemical CO2 reduction are considered promising approaches to mitigate CO2 accumulation in the atmosphere. Via these transformations, undesirable CO2 is not only removed from the air but also converted into valuable precursors such as CO, a chemical feedstock and a fuel source for energy production. However, these reactions involve multiple proton-coupled electron transfer (PCET) processes; hence, they require efficient molecular catalysts both to minimize the energy input and to tailor the reaction selectivity. Among the reported transition-metal-based molecular catalysts, manganese(I) tricarbonyl complexes such as [Mn(bpy)(CO)3X] (X = halide or pseudohalide) are promising electrocatalysts for CO2 reduction to CO. However, these monomeric Mn complexes are not contenders as photocatalysts for CO2 reduction due to their rapid photodegradation under UV and visible light. In this presentation, we report an efficient electrocatalyst for CO2 reduction via a cyanide-bridged di-manganese complex, {[Mn(bpy)(CO)3]2(μ-CN)}ClO4. In addition, unlike the Br-ligated precursor, the CN-bridged complex shows high resistance to undesirable photodegradation and facilitates photochemical reduction of CO2 to CO under 395 nm irradiation. Quantum yields approaching one are observed in this system.

Electrochemical and photochemical reduction of CO2 to CO: A cyanide-bridged di-manganese carbonyl complex

2019 Spring National Meeting

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