Polydentate ligand construction: intramolecular condensation reactions in the synthesis of imine-containing ligands

Intramolecular condensation reactions between coordinated polyamines and 2-ketoacids have been examined as part of a route to the synthesis of polydentate amino acid complexes. Imine-containing products have been isolated, and eight of these have been characterised by X-ray crystallographic techniques. In most cases, only a single product is isolated from these reactions. This selectivity can be attributed largely to the geometric constraints that are placed on a system by formation of the imine group. Reaction between a coordinated primary amine and a 2-ketoacid ligand appears to be a quite general route to polydentate iminoacid complexes.