| Summary: | A detailed investigation into the transition metal complexes of various chelating nitrogen donor ligands, form the basis of this thesis. Chapter 1 discusses the synthesis and co-ordination of a xylyl bridged bis-tacn ligand, which has been shown to form sandwich type structures. Chapters 2 and 3 discuss the synthesis and co-ordination behaviour of two novel tripodal tris-(pyridylpyrazolyl) ligand frameworks, L2 and L3. The ligand L2, forms stable mononuclear compounds which display predominantly trigonal prismatic geometries for a series of transition metals, with only a few exceptions (Cr(III), Re(I) and In(III)). For L1, the relationship between octahedral and trigonal prismatic character has been investigated, with varied d-electron configurations of the metal centre. Continuous shape mapping analysis (CShM) has been employed to assist in the quantification of their geometric distortions. For L3, a similar investigation has been discussed, where the potentially hexadentate ligand was found to form a series of five coordinate transition metal complexes, with predominately square pyramidal geometries. Chapter 4 investigates the co-ordination chemistry of a tetradentate bis-(pyrazolyl)bipyridine ligand with various di-cationic transition metals, forming distorted octahedral geometries, often involving co-ordination of the perchlorate counter ions. In Chapter 5, the synthesis of a novel tripodal bis-quinoline ligand, L5, has been introduced along with a detailed discussion of its coordination behaviour with a variety of transition metals, where the Cu(II) complex forms a trimeric structure involving co-ordination of a capping perchlorate counter-anion. The addition of a para-substituted phenyl-bromide group, as the third tripodal ‘arm’, gives this molecule potential for further functionalisation through coupling reactions. Chapter 6 investigates the coordination properties of Cu(II) and Re(I) with a similar bis-quinoline tripodal ligand, which contains a lipophilic butyl appendage. A series of luminescence experiments were performed for the Re(I) complex in order to determine its photophysical properties with varying levels of acid.
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