ic6b00079_si_003.pdf (3.61 MB)
Download fileRe(I) NHC Complexes for Electrocatalytic Conversion of CO2
journal contribution
posted on 07.03.2016, 00:00 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.