Characterization of Intermediate Oxidation States in CO Activation.

Redox chemistry during the activation of carbon dioxide involves changing the charge state in a CO molecular unit. However, such changes are usually not well described by integer formal charges, and one can think of COO functional units as being in intermediate oxidation states. In this article, we discuss the properties of CO and CO-based functional units in various charge states. Besides covering isolated CO and its ions, we describe the CO-based ionic species formate, oxalate, and carbonate. Finally, we provide an overview of CO-based functional groups and ligands in clusters and metal-organic complexes.