Taming early transition metals: the use of polydentate amido-donor ligands to create well defined reactive sites in reagents and catalysts

Ligand design in early transition metal chemistry has focussed recently on amide chemistry. The availability of two substituent positions at the amido N-donor atom allows its integration into ligand systems of both podand and macrocyclic topology. Amido functions may be combined with other donor functionalities which possess a different formal charge and chemical hardness and, more generally, a different thermodynamic and kinetic stability of their interaction with the metal centre. Early transition metal complexes containing polydentate amido-donor ligands not only display unprecedented patterns of reactivity but are the focus of recent developments in olefin polymerization catalysis.