The synthesis, spectroscopic and electrochemical characterisation of Ru(II) tris(heteroleptic) mononuclear and dinuclear complexes are described. Special attention is paid to the introduction of a triazole ligand to the metal sphere. Chapter 1 is an introductory chapter in that the basic concepts regarding Ru(II) polypyridyl chemistry are introduced and explained. The parent complex [Ru(bpy)3]2+ is examined along with its photochemical and photophysical properties. The replacement of a bpy ligand with that of a triazole is discussed as are the new properties associated with such a complex. Ultimately, this thesis focuses on the synthesis o f Ru(II) complexes containing three different ligands and so previously reported synthetic routes to such Ru(H) tris(heteroleptic) complexes are discussed. The next chapter introduces the synthetic and analytical methods used in the synthesis of tris(heteroleptic) complexes. The synthesis and purification of starting and reference materials used throughout the thesis are discussed. Having introduced tris(heteroleptic) complexes in the opening chapter, Chapter 3 takes a practical look at the various synthetic strategies used to synthesise such complexes. Previously reported synthetic routes are explored for their suitability in allowing a triazole ligand to be incorporated into tris(heteroleptic) compounds. The methods have been subdivided into four categories, namely the [Ru(bpy)Cl3], [Ru(bpy)(DMSO)Cl2], decarbonylation and photosubstitution methods. The trial 1,2,4-triazole complex [Ru(bpy)(Me2bpy)(pytrz)]+ was best synthesised and purified by a synthetic route which included the photolysis of [Ru(bpy)(CO)2Cl2] in MeCN to produce material that yielded the dichloride [Ru(bpy)(Me2bpy)Cl2]. This dichloride was successfully reacted with the 1 ,2,4-triazole ligand to produce the tris(heteroleptic) complex. With a successful method of incoiporating a triazole ligand, Chapter 4 describes the synthesises of a series of such complexes. Two more dichlorides, [Ru(bpy)(phen)Cl2] and [Ru(bpy)(dpp)Cl2] are prepared and together with [Ru(bpy)(Me2bpy)Cl2] are successfully reacted with the bridging ligands Hbpt and Hbpzt to create mononuclear tris(heteroleptic) complexes. These complexes are characterised and crystal structures of both a bpt' and b p z f complex are reported. The photochemical and photophysical properties of the complexes are investigated and compared to those of analogous bis(heteroleptic) complexes such as [Ru(bpy)2(bpt)]3+. The difference in Hbpt and Hbpzt bridging ligands is also discussed. Chapter 5 follows on from Chapter 4 and investigates the possibility of creating dinuclear tris(heteroleptic) complexes. The dinuclear analogues of the Chapter 4 mononuclear complexes are prepared, along with a range of dpp dinuclear complexes. In some cases only one metal centre is tris(heteroleptic) while in others both are designed this way. The properties of these new complexes are explored and compared with the properties of the mononuclear compounds. Finally, the results of the work undertaken are summarised with suggestions on further possible research directions.