Some properties of metal complexes containing one metal-carbon bond

The physical and chemical properties, including electronic absorption, infra-red, and 1H n.m.r. spectra of cobalt(III) complexes of the type CoA4XY, where A4 can be corrin, a Schiffs base, or dimethylglyoxime and X a carbon ligand, are discussed in terms of the change in electron density in the complex. It is shown that alkyl ligands act as strong donors, often giving rise to five-co-ordinate complexes. The relationship of the properties of these five-co-ordinate cobalt(III) complexes to those of analogous cobalt(II) nickel(II) and palladium(II) complexes is discussed and the difference between the cobalt-carbon bond in the five- and six-co-ordinate complexes considered.