This thesis describes the synthesis and characterisation of novel complexes bearing monoanionic phenolateamine ligands and explores their catalytic behaviour in the ring opening polymerisation of lactide and in the polymerisation of ethylene.
Chapter 1 introduces and reviews various aspects of the coordination chemistry of phenolateamine ligands and is followed by an introduction to the field of lactide polymerisation. Chapter 2 describes the preparation of several potentially tetradentate proligands via the Mannich reaction. The ligands presented have various combinations of donors, chain length and substituents on the phenyl backbone. The synthesis and characterisation of several novel main group complexes (K, Ca and Al) using these ligands is presented. The calcium bis-chelate complexes are shown to be highly active in the ring opening polymerisation of lactide. Chapter 3 introduces a new family of zinc species stabilised by these ligands. The coordination chemistry of zinc alkyls and alkoxides is shown to be dependent on ligand structure, most notably on the choice of heteroatom donor and phenolate backbone substituent. The zinc alkoxides are efficient
initiators in the polymerisation of rac-lactide, with the catalytic activity influenced by the choice of coordinated ligand. The highest activity is observed with ligands containing two neutral oxygen donors in combination with bulky phenolate substituents. After a brief introduction to the field of olefin polymerisation, Chapter 4 describes the synthesis and characterisation of a wide range of transition metal complexes (Ti, V, Cr, Fe, Co and Ni) and discusses their activity as precatalysts in the polymerisation of ethylene. Full experimental details for Chapters 2-4 are presented in Chapter 5.