Twenty nine new nitrogen-containing heterocyclic ligands have been prepared, and characterised. The ligands all contain a central arene core, to which are appended two or more heterocycles via spacer groups. Benzene, naphthalene, biphenyl, binaphthalene or triphenylene has been used as the central arene core, while the heterocycles used are pyridine, quinoline, 1 ,2,4-triazole, and benzotriazole. The coordination chemistry of the majority of these ligands has been investigated by their reactions with transition metals with the aim of constructing metallosupramolecular architectures. Such assemblies are constructed using the coordination bond as the major intermolecular interaction, as well as weaker secondary interactions including π-π stacking interactions and hydrogen bonds. The cyclopalladation chemistry some of these ligands, and of five previously prepared ligands, has also been investigated. In particular, a number of doubly palladated compounds containing six-membered chelate rings have been prepared. Such cyclopalladation reactions have been shown to be reversible. This, coupled with the appropriate reaction conditions, has allowed the regiochemistry of the products of the cyclopalladation reaction to be controlled in certain systems. Techniques used to characterise the ligands and complexes include NMR spectroscopy, mass spectrometry, elemental analysis, and X-ray crystallography. The X-ray crystal structures of thirty-six complexes have been accurately determined, and the structures of two further complexes have been determined with less accuracy. The variety of ligands resulted in the preparation of a range of complexes of diverse structural types. The structures determined include one- and two-dimensional coordination polymers, a triple helicate, macrocycles, chelate complexes and supramolecular boxes. The triple helicate is the first constructed from trigonal metal termini. The polymers include a molecular ladder that is the first to contain a ligand as the T-connector and metals as the linear connectors.