S,S'-diphenylsulfimide, Ph2SNH, 1, is an excellent ligand that readily forms N-bound complexes with a range of transition metals. Its importance as a ligand is enhanced by two significant features of the resulting complexes: (1) the strong hydrogen bonding interactions between the NH unit and the counterions; and (2) the ligand's ability to stabilise unusual structural combinations. By varying the counterions, the hydrogen bonding pattern can be changed and this affects the geometry at the metal centre. The anion also plays an important role in determining the coordination number of the metal. The hydrogen bonding interactions have been utilised to prepare extended arrays by the inclusion of appropriate outer sphere, bridging ligands, such as terephthalate and fumarate into the system. The fixation of atmospheric CO2 has been observed in a number of systems leading to the formation of both a bicarbonate dimer and a metal-bound carbonate ligand. These act as hydrogen bonding acceptors to give extended 2-D networks.

This thesis explores the influence of molecular and electronic structure on the reactivity of some small inorganic complexes, beginning with a review of the nature and properties of metal-hydrogen and metal-carbon bonds of early transition metals and of their importance in catalysis. A series of cationic niobium methyl complexes, TpMe2NbMe(L)(MeC=CMe) BArf4 (L = OEt2, THF, 0'Pr2, PMe2Ph and PEt/j) was synthesised and characterised by NMR spectroscopy. Small-scale reactions at low temperatures resulted in the formation of a highly unstable cation, which was stabilised by co-ordination with a series of small electron donor ligands (L). Low temperature NMR studies were used to characterise the resulting air- and temperature-sensitive complexes in solution. One adduct (L = OEt2) was isolated in the solid state and its structure, determined by X-ray crystallography, accorded with the interpretation of its NMR spectrum. The influence of L on the reactivity and stability of the complexes was explored, with preferred co-ordination demonstrated through ligand exchange reactions. Initial catalytic assays established a level of activity warranting further investigation. A high quality crystal of (Bz3Ti)20 was sujected to an experimental charge density study, assisted by an 'Atoms in Molecules' (AIM) theory analysis. This yielded insights into the charge distribution at the Ti and O centres demonstrating the presence of 'ligand induced charge concentration' (LICC). Density functional theory (DFT) calculations were carried out on (Bz3Ti)20 producing theoretical charge densities in excellent agreement with the experimental results. X-ray crystallography studies were conducted on the intermediates in the synthesis of MeTi(NMe2)3, BrTi(NMe2)3 and the novel complex {Ti(NMe2)20}2Ti3(NMe2)60Br2. IR and NMR spectroscopies were used to explore the nature of the Ti-Me moiety in MeTi(0'Pr)3 no a-agostic interactions were discovered. Variable energy photoelectron spectroscopy has been used for an in-depth study of the electronic structure, including core electrons, of some small, tetrahedral inorganic compounds. The bonding in the industrially used catalyst MeRe03 was studied through the variation of the valence electron band intensities over a wide range of photon energies. Investigation of the electronic structure at the metal centres of the series of metalloborohydrates Zr(BH4)4, Hf(BH4)4 and U(BH4)4 was carried out in a similar manner. Calculation of relative partial photoionisation cross-sections and derived branching ratios along with observation of features such as shape and giant resonance gave insight into the relative ligand and metal contributions to the orbitals. The core electrons and absorption edges of the complexes were also studied. Experimental results showed good correlation with density functional theory calculations.

This Thesis describes three broad areas: i) the synthesis of Fe and Ru complexes and the development of new catalytic systems for the dehydrocoupling of phosphine and amine-borane complexes, ii) mechanistic and reactivity studies of the dehydrocoupling of amine-borane adducts catalyzed by Rh complexes and (iii) the synthesis of a new amine-borane adduct and its dehydrogenation and hydrogenation reactivity studies.

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Over the last two decades, the implementation of sterically demanding, bowl-shaped l11-terphenyl molecules as ligands in organometallic chemistry has facilitated the synthesis of novel coordination complexes due to their ability to kinetically stabilise electronically and coordinatively unsaturated, highly reactive metal centres. Although early studies were primarily concerned with the main group metals, in recent years focus has shifted somewhat to the utilisation of these ligands with transition metals, following a number of high-profile advances including most notably the isolation of the first formally quintuple bond between two metal centres in 2005. Despite the recent successes afforded by l11-terphenyls in fundamental p and dblock chemistry, their utilisation in concert with transition metals is still in its infancy, evidenced by a paucity of examples in the literature. In order to address this shortage and explore both the structural and chemical propetties of such species, the work discussed herein documents the synthetic utilisation of 2,6-Ar2C6H3 - (AI' = Mes, l -Naph) in the stabilisation of a series of disubstituted d-block bis(m-terphenyl) compounds, in addition to a number of heteroleptic, monosubstituted complexes. The homoleptic two-coordinate Zn(II) complex (2,6-Naph2C6H3)2Zn (6) and the three-coordinate T-shaped (2,6-Naph2C6H3)2M(OEt2) (M = Cd, 7; Hg, 8) comprise the first crystallographically verified Group 12 bis(l11-terphenyl) series, with only one such mercury bis(l11-terphenyl) complex having previously been reported.

Following the discovery that a single molecule can behave as a magnet, the field of research on magnetism has become of great interest to scientists. A large number of polynuclear compounds have been produced and studied worldwide over the past two decades, in an effort to obtain better single molecule magnets (SMMs). The synthesis of such compounds involves mainly first row transition metals and a wide range of bridging ligands.

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