Coordination chemistry of Co(III) complexes of an azetidine-derived quadridentate amine and a related macrocycle

The azetidine ring of a quadridentate ligand is protected from nucleophilic ring-opening by coordination and imparts a rigidity to the ligand which limits the stereoisomerism of its Co(III) complexes, crystal structures of which show evidence for extensive hydrogen-bonding and lipophilic interactions.