We report a novel metal-free chemical reduction of CO2 by a benzimidazole-based organo-hydride, whose choice was guided by quantum chemical calculations. Notably, benzimidazole-based hydride donors rival the hydride-donating abilities of noble metal-based hydrides such as [Ru(tpy)(bpy)H]+ and [Pt(depe)2H]+. Chemical CO2 reduction to the formate anion (HCOO-) was carried out in the absence of biological enzymes, a sacrificial Lewis acid, or a base to activate the substrate or reductant. 13CO2 experiments confirmed the formation of H13COO- by CO2 reduction with the formate product characterized by 1H-NMR, 13C-NMR, and ESI-MS. In addition, the organo-hydride was electrochemically regenerated from the benzimidazolium cation in quantitative yield, demonstrating its tremendous potential for electrocatalytic CO2 reduction. These results represent a metal-free system that serves as a proof of concept for electrocatalytic CO2 reduction with sustainable organo-hydrides.

Benzimidazoles as recyclable metal-free hydrides for CO2 reduction to formate

2019 Spring National Meeting

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