Developments in the synthesis and coordination chemistry of macrocyclic Schiff base ligands

The use of metal ions as templates in the synthesis of a range of macrocyclic Schiff base ligands varying in size (15-30 member atoms), in the number and nature of the potential donor atoms, and in flexibility is described. Factors controlling the course of the reactions are discussed. Open-chain intermediates have been isolated in several cases and mechanisms for the cyclizations are proposed. The structures, properties and reactions of the macrocyclic complexes, including the use of some binuclear copper complexes as receptors for small bridging molecules and ions (e.g. pyrazine, imidazolate ion), are reported.