Synthetic and kinetic studies of macrocyclic metal complexes

Abstract

The chemistry of a series of pentaaza and hexaaza macrocycles formed by the metal directed condensation of formaldehyde, diamines and primary amines has been investigated. Structural studies were carried out and the results used to determine the extent of any long range interactions between the coordinated metal ion and non-coordinating amino groups. The effect of the uncoordinated tertiary amine on the square planar-octahedral spin equilibria was also studied. Chapter 2 investigates kinetic aspects of the chemistry of binuclear complexes of hexaaza macrocycles. The acid catalysed metal dissociation reactions of the copper(II) complexes of three ligands were studied. It was found that the two metal centres in such complexes act independently of each other. Activation parameters for the metal dissociation reactions have been determined. Chapter 3 discusses cobalt(III) complexes of the tetraaza macrocycle [15]aneN₄. Kinetic and mechanistic studies have been carried out to study the decarboxylation reaction of [Co([15]aneN ₄)(CO₃)]⁺. A mechanism for this reaction is described. The kinetics ofthe hydrolysis of [Co([15]aneN₄)Cl₂]⁺ have also been investigated. The ring closure reactions of a linear β-aminoketone copper(II) complex to form the macrocyclic complex [Cu(trans[14]dieneN₄)]²⁺ have been studied kinetically. A mechanism involving an intramolecular reaction with a coordinated hydroxide group has been proposed. Attempts to synthesise macrocyclic tetraamide complexes via a literature method are described Evidence is presented which suggests that the preparation of such complexes by metal template directed condensation of diacids and diamines is not viable and this view has been confirmed by crystallographic studies.