Carbon dioxide complexes: Bonding modes and synthetic methods

A critical survey on the literature on CO2 metal complexes is provided. A re-evaluation of all known CO2 complexes reveals the existence of several bonding modes, which have not been recognized as separate classes so far. This review further provides suggestions on alternative interpretations of the bonding in reported complexes. The accurate classification of the bonding situation as well as the oxidation states of carbon and the metals involved in binding CO2 allowed for establishing a generalized summary of all known synthetic methods. Finally, a short overview of reductive carbon dioxide transformations at metal centers is given.