A Molecular Ruthenium Electrocatalyst for the Reduction of Carbon Dioxide to CO and Formate

The
use of a bulky bipyridine ligand, 6,6′-dimesityl-2,2′-bipyridine
(mesbpy), to enable the reduction of carbon dioxide by a Ru-based
molecular electrocatalyst is reported. Under catalytic conditions,
this compound exhibits turnover frequencies of 1300 s–1 and 95% Faradaic efficiency for the production of CO and H2O from CO2 in the presence of Brønsted acids. Mechanistic
electrochemical and spectroelectrochemical studies, supplemented by
the direct synthesis of relevant intermediates, indicate that this
behavior is the result of the cooperative redox response of the bipyridine
ligand and Ru metal center at negative potentials, as well as the
inhibition of Ru–Ru bond formation through steric interactions.