The solvent extraction of metal chelates has been used for a long time for separation and determination of metal ions. The first quantitative description of the extraction process was, however, not made until 1941 when Kolthoff and Sandell compared experimental data with theoretical predictions for the extraction of metal dithizonates. They found that the theory they proposed was valid under wide experimental conditions. However, the systems used by Kolthoff and Sandell were simple ones and hence relatively simple theory was used to successfully explain their behaviour. In practice solvent extraction systems are complicated by other factors, e.g. hydrolysis, polymerisation and complex formation in the aqueous phase. It has subsequently become apparent that such factors have an important influence on the solvent extraction of chelates. Several authors have published reports since 1941 on the theory of solvent extraction of metal chelates which take these factors into account. In particular two publications by Irving, Rossotti and Williams and Stary (chapter 3) should be noted for their comprehensive treatment of the subject. The influence of these factors will be discussed in the following sections.

An investigation into the chemistry of solutions of titanium dioxide in fused alkali metal borates has been made, with the emphasis on the ability of the alkali borate melts to dissolve TiO2 and subsequently crystallize TiO2 and/or complex alkali metal titanates. The preparation and properties of potassium titanates with K2O/TiO2 mol ratio ≤1 has been studied. In addition the thermal decomposition of potassium hexafluorotitanate monohydrate (reported to yield potassium tetratitanate) has been investigated. The decomposition product has been identified as an oxyfluorotitanate. The compounds crystallized on slow cooling of alkali borate + TiO2 melts have been identified. The titanium containing product(s) have been correlated with the concentration of borate groups containing non-bridging oxygens, which depends on the alkali metal cation. Phase diagrams for the M2O.B2O3 + TiO2 (M = Na, K) systems have been obtained. Mass transport in M2O.2B2O3 + TiO2 (M = Li, Na, K) systems has been studied, via measurements of electrical conductivity, as a function of temperature and TiO2 concentration. Additional information on the alkali borate melts has been obtained from measurements of the optical basicity of M2O + B2O3 (M = Li, Na, K, Rb, Cs) glasses, using Pb(II) as probe ion. The results of these measurements have confirmed that the nature of the alkali metal cation significantly affects the basicity of fused alkali borate solvents. Extraction of TiO2 from ilmenite and titaniferous slag, using selected low-basicity alkali borate solvents has been attempted. The results indicate that TiO2 may be separated from ilmenite in essentially a one-step process.

The solvent extraction of metal chelates has been used for a long time for separation and determination of metal ions. The first quantitative description of the extraction process was, however, not made until 1941 when Kolthoff and Sandell compared experimental data with theoretical predictions for the extraction of metal dithizonates. They found that the theory they proposed was valid under wide experimental conditions. However, the systems used by Kolthoff and Sandell were simple ones and hence relatively simple theory was used to successfully explain their behaviour. In practice solvent extraction systems are complicated by other factors, e.g. hydrolysis, polymerisation and complex formation in the aqueous phase. It has subsequently become apparent that such factors have an important influence on the solvent extraction of chelates. Several authors have published reports since 1941 on the theory of solvent extraction of metal chelates which take these factors into account. In particular two publications by Irving, Rossotti and Williams and Stary (chapter 3) should be noted for their comprehensive treatment of the subject. The influence of these factors will be discussed in the following sections.

An investigation into the chemistry of solutions of titanium dioxide in fused alkali metal borates has been made, with the emphasis on the ability of the alkali borate melts to dissolve TiO2 and subsequently crystallize TiO2 and/or complex alkali metal titanates. The preparation and properties of potassium titanates with K2O/TiO2 mol ratio ≤1 has been studied. In addition the thermal decomposition of potassium hexafluorotitanate monohydrate (reported to yield potassium tetratitanate) has been investigated. The decomposition product has been identified as an oxyfluorotitanate. The compounds crystallized on slow cooling of alkali borate + TiO2 melts have been identified. The titanium containing product(s) have been correlated with the concentration of borate groups containing non-bridging oxygens, which depends on the alkali metal cation. Phase diagrams for the M2O.B2O3 + TiO2 (M = Na, K) systems have been obtained. Mass transport in M2O.2B2O3 + TiO2 (M = Li, Na, K) systems has been studied, via measurements of electrical conductivity, as a function of temperature and TiO2 concentration. Additional information on the alkali borate melts has been obtained from measurements of the optical basicity of M2O + B2O3 (M = Li, Na, K, Rb, Cs) glasses, using Pb(II) as probe ion. The results of these measurements have confirmed that the nature of the alkali metal cation significantly affects the basicity of fused alkali borate solvents. Extraction of TiO2 from ilmenite and titaniferous slag, using selected low-basicity alkali borate solvents has been attempted. The results indicate that TiO2 may be separated from ilmenite in essentially a one-step process.

The solvent extraction of metal chelates has been used for a long time for separation and determination of metal ions. The first quantitative description of the extraction process was, however, not made until 1941 when Kolthoff and Sandell compared experimental data with theoretical predictions for the extraction of metal dithizonates. They found that the theory they proposed was valid under wide experimental conditions. However, the systems used by Kolthoff and Sandell were simple ones and hence relatively simple theory was used to successfully explain their behaviour. In practice solvent extraction systems are complicated by other factors, e.g. hydrolysis, polymerisation and complex formation in the aqueous phase. It has subsequently become apparent that such factors have an important influence on the solvent extraction of chelates. Several authors have published reports since 1941 on the theory of solvent extraction of metal chelates which take these factors into account. In particular two publications by Irving, Rossotti and Williams and Stary (chapter 3) should be noted for their comprehensive treatment of the subject. The influence of these factors will be discussed in the following sections.

An investigation into the chemistry of solutions of titanium dioxide in fused alkali metal borates has been made, with the emphasis on the ability of the alkali borate melts to dissolve TiO2 and subsequently crystallize TiO2 and/or complex alkali metal titanates. The preparation and properties of potassium titanates with K2O/TiO2 mol ratio ≤1 has been studied. In addition the thermal decomposition of potassium hexafluorotitanate monohydrate (reported to yield potassium tetratitanate) has been investigated. The decomposition product has been identified as an oxyfluorotitanate. The compounds crystallized on slow cooling of alkali borate + TiO2 melts have been identified. The titanium containing product(s) have been correlated with the concentration of borate groups containing non-bridging oxygens, which depends on the alkali metal cation. Phase diagrams for the M2O.B2O3 + TiO2 (M = Na, K) systems have been obtained. Mass transport in M2O.2B2O3 + TiO2 (M = Li, Na, K) systems has been studied, via measurements of electrical conductivity, as a function of temperature and TiO2 concentration. Additional information on the alkali borate melts has been obtained from measurements of the optical basicity of M2O + B2O3 (M = Li, Na, K, Rb, Cs) glasses, using Pb(II) as probe ion. The results of these measurements have confirmed that the nature of the alkali metal cation significantly affects the basicity of fused alkali borate solvents. Extraction of TiO2 from ilmenite and titaniferous slag, using selected low-basicity alkali borate solvents has been attempted. The results indicate that TiO2 may be separated from ilmenite in essentially a one-step process.

An investigation into the chemistry of solutions of titanium dioxide in fused alkali metal borates has been made, with the emphasis on the ability of the alkali borate melts to dissolve TiO2 and subsequently crystallize TiO2 and/or complex alkali metal titanates. The preparation and properties of potassium titanates with K2O/TiO2 mol ratio ≤1 has been studied. In addition the thermal decomposition of potassium hexafluorotitanate monohydrate (reported to yield potassium tetratitanate) has been investigated. The decomposition product has been identified as an oxyfluorotitanate. The compounds crystallized on slow cooling of alkali borate + TiO2 melts have been identified. The titanium containing product(s) have been correlated with the concentration of borate groups containing non-bridging oxygens, which depends on the alkali metal cation. Phase diagrams for the M2O.B2O3 + TiO2 (M = Na, K) systems have been obtained. Mass transport in M2O.2B2O3 + TiO2 (M = Li, Na, K) systems has been studied, via measurements of electrical conductivity, as a function of temperature and TiO2 concentration. Additional information on the alkali borate melts has been obtained from measurements of the optical basicity of M2O + B2O3 (M = Li, Na, K, Rb, Cs) glasses, using Pb(II) as probe ion. The results of these measurements have confirmed that the nature of the alkali metal cation significantly affects the basicity of fused alkali borate solvents. Extraction of TiO2 from ilmenite and titaniferous slag, using selected low-basicity alkali borate solvents has been attempted. The results indicate that TiO2 may be separated from ilmenite in essentially a one-step process.

The coordination chemistry of compounds featuring P-P and P—Sb bonds has been investigated to define the fundamental features of bonding in these systems. New reaction methodologies to form P—P bonds have been evolved based on careful consideration of bond strengths in the gas and condensed phase. Insights revealed from systematic studies of molecular structures have been used to augment and expand the scope of existing models for structural prediction (e.g. VSEPR theory). Unique classes of catena-antimony compounds have been discovered, illustrating a remarkable structural and electronic diversity for this heavy p-block metal. Detailed mechanistic examinations have revealed a previously unrecognized mode of ligand activation for phosphine complexes of very electrophilic acceptors. Stable sources of the hitherto unisolated and highly reactive tris-triflate reagents, E(OTf)3 (E = P, As, Sb, Bi), have been prepared and their coordination chemistry as Lewis acids and oxidizing agents has been mapped. Collectively, the findings described here span a range of coordination chemistry paradigms for p-block elements that may be broadly applicable across the periodic table. A robust plan has been proposed for applying these insights towards the preparation of fundamentally interesting molecular frameworks and towards new strategies for small molecule activation. / Graduate / 0488 / 0485

This Thesis describes the syntheses, characterisation and reactivity of rare earth metal boryl and gallyl compounds. Experimental and computational studies were performed to investigate the structure and bonding in these compounds. <b>Chapter 1</b> introduces key metal-boryl and metal-gallyl compounds of the s, p, d and f-blocks via literature review. <b>Chapter 2</b> describes the syntheses, structures and bonding analyses of rare earth metal boryl compounds. A short introduction to rare earth metal cations is given. Chapter 3</b> describes the syntheses, structures and bonding analyses of rare earth metal gallyl compounds. The preparation of a new class of rare earth metal cations will also be reported. A short introduction to rare earth metal amidinates is given. <b>Chapter 4</b> presents reactivity studies of the rare earth metal gallyl compounds described in Chapter 3. To facilitate a direct structure and reactivity comparison, the corresponding boryl compounds were also synthesised. The results of a comprehensive DFT computational study to investigate the structure and bonding in these compounds are also presented. A short introduction to metalelement and metalmetal bond reactivity is given. <b>Chapter 5</b> presents full experimental procedures and characterising data for the new compounds reported. <b>Appendix<b> <b>CD Appendix</b> contains .cif files for all new crystallographically characterised compounds described.

This work was initially launched to study the synthesis of low-valent group 13 compounds bearing the bis(imino)pyridine ligand framework. Since its inception, this project has grown beyond the boundaries of group 13 to include low valent tin, silver, and rhenium. Alongside the reports of novel coordination compounds, we utilized computational chemistry to uncover unprecedented interactions which challenge conventional concepts of bonding. Synthesis, characterization, and complimentary computational studies are presented herein. Chapter 1 presents a historical overview of the bis(imino)pyridine ligand as well as our synthetic methodology and characterization of new ligand variants we have contributed to the literature. Chapter 2 presents the synthesis of a series of In(I) and In(III) bis(imino)pyridine complexes with varied sterics. Ligand-metal interaction and effect of ligand steric bulk on complex stability, as well as computational studies highlighting weak covalent interactions will be discussed. Chapter 3 presents the synthesis of Ga(III) bis(imino)pyridine complexes. Reactivity with “GaI” synthon as well as varied-stoichiometry one-pot synthesis attempts to generate low valent Ga-bis(imino)pyridine complexes will be discussed. Chapter 4 presents the synthesis of a series of Tl(I) bis(imino)pyridine complexes with varied sterics analogous to the approach taken with indium(I). Unprecedented weak ligand-metal as well as Tl-arene interactions will be discussed. Chapter 5 presents the synthesis of a series of Sn(II) bis(imino)pyridine complexes with varied sterics and halide substituents. Preferential cation-anion pair formation and attempted reactivity will be discussed. Chapter 6 presents the synthesis of a series of Ag(I) bis(imino)pyridine complexes with varied sterics. Resulting ligand-metal interactions as well as reactivity towards Lewis basic donor ligands will be discussed. Chapter 7 presents the synthesis of first crystallographically authenticated examples of rhenium(I) pincer complexes utilizing the bis(imino)pyridine ligand. Chapter 8 presents a general conclusion to the work.