Carbon monoxide (CO) can be used as a starting material for many valuable chemicals. One promising way to produce CO is via the reduction of carbon dioxide (CO2) to CO. However, reduction of CO2 to CO is a formidable challenge, and a suitable catalyst is required for this reaction to occur with enough speed, efficiency and selectivity. When [M(CO)3(R-bpy)X] complexes (M = Re or Mn, R-bpy = bipyridine or bipyridine derivative, and X = halide) are reduced in situ they can catalyze reduction CO2 to CO with good selectivity. For most CO2 reduction catalysts of this type, catalysis occurs at or near the second of two one-electron reduction events. The reduction pathway involves protonation of CO2, and recently addition of an intramolecular Brønsted acid in the form of a phenol substituent on the bipyridine ligand of a [Mn(CO)3(R-bpy)Br] catalyst was found to result in an enhanced catalytic current at a moderate overpotential. We have synthesized several different bipyridine derivatives in order to systematically study the effect of the Ka and positioning of an intramolecular Brønsted acid substitent on the ability of [M(CO)3(R-bpy)X]-type catalysts to reduce CO2 to CO. The syntheses, characterization, electrochemistry, and catalytic activities of these catalysts are reported.

Effects of acid strength and position of an intramolecular acidic functional group on the catalytic reduction of CO2 to CO

253rd National Meeting (2017)

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.