Metal Carbonyls

Abstract

Carbon monoxide forms a host of metal carbonyl complexes, at least one for every transition metal. Mononuclear, polynuclear, and heteronuclear metal carbonyls are all known. The complexes, of general formula M x (CO) y , may be charged or neutral; the metal or metals are in low, zero, or negative oxidation states. Synthesis of the metal carbonyls usually proceeds either from the reduction of the corresponding metal salt, although direct reaction between the metal and CO takes place for certain elements. Clusters are usually made via condensation of lower molecular weight compounds. The structure and bonding of the metal carbonyls, including those of cluster compounds, follow well‐defined rules. Metal carbonyls are extremely useful as reagents in organic synthesis and catalysts, playing a pivotal role in both the Reppe and the oxo processes, as well as in the preparation of fine chemicals.