ic6b00079_si_003.pdf (3.61 MB)
Download fileRe(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 AgarwalThe 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.