Re(I) NHC Complexes for Electrocatalytic Conversion
of CO2

Stanton, Charles J.; Machan, Charles W.; Vandezande, Jonathon E.; Jin, Tong; Majetich, George F.; Schaefer, Henry F.; Kubiak, Clifford P.; Li, Gonghu; Agarwal, Jay

doi:10.1021/acs.inorgchem.6b00079.s003

ic6b00079_si_003.pdf (3.61 MB)

Re(I) NHC Complexes for Electrocatalytic Conversion of CO₂

journal contribution

posted on 2016-03-07, 00:00 authored by Charles J. Stanton, Charles W. Machan, Jonathon E. Vandezande, Tong Jin, George F. Majetich, Henry F. Schaefer, Clifford P. Kubiak, Gonghu Li, Jay Agarwal

The modular construction of ligands around an N-heterocyclic carbene building block represents a flexible synthetic strategy for tuning the electronic properties of metal complexes. Herein, methylbenzimidazolium-pyridine and methylbenzimidazolium-pyrimidine proligands are constructed in high yield using recently established transition-metal-free techniques. Subsequent chelation to ReCl(CO)₅ furnishes ReCl(N-methyl-N′-2-pyridylbenzimidazol-2-ylidine)(CO)₃ and ReCl(N-methyl-N′-2-pyrimidylbenzimidazol-2-ylidine)(CO)₃. These Re(I) NHC complexes are shown to be capable of mediating the two-electron conversion of CO₂ following one-electron reduction; the Faradaic efficiency for CO formation is observed to be >60% with minor H₂ and HCO₂H production. Data from cyclic voltammetry is presented and compared to well-studied ReCl(2,2′-bipyridine)(CO)₃ and MnBr(2,2′-bipyridine)(CO)₃ systems. Results from density functional theory computations, infrared spectroelectrochemistry, and chemical reductions are also discussed.