The coordination chemistry of carbon dioxide and its relevance for catalysis: a critical survey

The ability of carbon dioxide to act as a ligand in transition metal complexes is now well documented and several coordination modes of CO 2 have been described. Spectroscopic methodologies allowing the characterization of CO 2 complexes even if crystallographic data are not available have now been developed. The binding of CO 2 to a metal centre generally leads to “activation” of the CO 2 molecule, and various reactions of coordinated CO 2 are known. However, activation by coordination is not a necessary prerequisite for catalytic conversion of carbon dioxide to useful chemicals. Recent theoretical and experimental work suggests that only weak interactions between CO 2 and the active metal centre are sufficient to bring about catalytic reactions involving the formal insertion of CO 2 in an MX bond as a key step.