Some Tetra-Aza Macrocyclic Ligands and Their Metal-Ion Complexes

Abstract

In Part I of this thesis the results, and conclusions deduced therefrom, of a study of the mechanism of the reaction between 1,3-diaminopropane nickel(II) salts and acetone are presented. The final products of this reaction are nickel(II) complexes of a sixteen-membered macrocyclic ligand (2,4,4,10,12,12-hexamethyl-1,5,9,13-tetra-azacyclohexadeca-1,9-diene) with two secondary amino, and two imino, donor groups. The chemistry of nickel(II) complexes of this macrocycle has been studied, and the results have been compared with the properties observed for complexes of related macrocycles. In Part II the results and conclusions obtained from a study of nickel(II) and copper(II) complexes formed by the fourteen-membered macrocycle 5,12-dimethyl-7, 14-diphenyl-1,4,8,11-tetra-azacyclotetradeca-4,11-diene, are presented. This macrocycle can adopt either planar (1,2,6,4-) or folded (1,2,6,3-) coordination. From observations on the chemical behaviour coupled with a study of molecular models, the positions of the substituent groups and the configurations at the chiral carbon centres have been assigned. The configurations at the coordinated secondary nitrogen atoms have also been assigned for both planar and folded coordination. The chemistry of this macrocycle has also been compared with that of related fourteen-membered macrocyclic dienes. In Part III the chemistry of nickel(II), and some copper(II), complexes formed by three isomeric 5,12-dimethyl-7,14-diphenyl-1,4,8,11-tetra-azacyclotetradecanes (formed by reduction of the diene described above) is described. From an analysis of the preferred conformations of the individual chelate rings coupled with experimental observations, configurations have been assigned to the chiral carbon centres of the three cyclic tetra-amines. The configurations which the coordinated secondary nitrogen centres would be expected to adopt in planar or folded coordination have also been assigned from a analysis of the preferred conformations of the chelate rings.