4 vs. 5: Mechanistic studies clarify the role of chelation number in the structure-activity relationship in CO₂ reduction catalyzed by pyridiyldiimine-functionalized cobalt macrocyclic catalysts.

Abstract

Mechanistic studies with characterizing crucial intermediates are indispensable in elucidating the promotive effects of ligand modifications, which thereby serve as useful orientations for rational optimization of molecular catalysts for CO₂ reduction. Herein we investigate the catalytic mechanism of a Co^II catalyst bearing a tetra-dentate macrocyclic ligand by electrochemical and spectroelectrochemical techniques, where its unstable Co⁰ active species under catalytic conditions accounts for its lower catalytic performance compared to that of another Co^II catalyst featuring a similar penta-dentate macrocyclic ligand.