Queenie Wai Yan Ip. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2003. / Includes bibliographical references (leaves 91-94). / Abstracts in English and Chinese. / Acknowledgements --- p.ii / Abstract --- p.iii / 摘要 --- p.v / List of Abbreviations --- p.xii / List of Compounds Synthesized --- p.xiii / Chapter CHAPTER 1 --- Syntheses and Characterizations of Pyrazyl-Linked Bis(l-Aza-Allyl) Alkali-Metal Complexes / Chapter 1.1. --- Introduction --- p.1 / Chapter 1.1.1. --- A General Review of 1-Aza-Allyl Ligands --- p.1 / Chapter 1.1.2. --- A General Review of Group 1 Alkali-Metal Complexes Containing Bis(l-Aza-Allyl) Ligands --- p.6 / Chapter 1.2. --- Objective --- p.9 / Chapter 1.3. --- Results and Discussion --- p.11 / Chapter 1.3.1. --- Preparation and Characterization of Pyrazyl-Linked Bis(l-Aza-Allyl) Di-Lithium Complex --- p.11 / Chapter 1.3.1.1. --- "A Modified Synthesis of Pyrazyl-Linked Bis(l-Aza-Allyl) Di-Lithium Complex [Li2{{N(SiMe3)C(But)C(H)}2C4H2N2-2,3}(THF)2]2 (1)" --- p.11 / Chapter 1.3.1.2. --- Physical and Spectroscopic Properties of Complex 1 --- p.11 / Chapter 1.3.1.3. --- Molecular Structure of Complex 1 --- p.12 / Chapter 1.3.2. --- Preparation and Characterization of Pyrazyl-Linked Bis(l-Aza-Allyl) Di-Sodium and Di-Potassium Complexes --- p.15 / Chapter 1.3.2.1. --- "Preparation of Pyrazyl-Linked Bis( 1 -Aza-Allyl) Di-Sodium complex [Na2{{N(SiMe3)C(But)C(H)}2C4H2N2-2,3}(THF)2]2 (2) and Di-Potassium Complex [K2{{N(SiMe3)C(But)C(H)}2C4H2N2-2,3}- (THF)3]2 (3)" --- p.15 / Chapter 1.3.2.2. --- Physical and Spectroscopic Properties of Complexes 2 and 3 --- p.15 / Chapter 1.3.2.3. --- Molecular Structures of Complexes 2 and 3 --- p.16 / Chapter 1.4 --- Experimental Section --- p.23 / Chapter 1.5 --- References --- p.25 / Chapter CHAPTER 2 --- Syntheses and Characterizations of Pyrazyl-Linked Bis(l-Aza-Allyl) Group 2 and 12 Metal Complexes / Chapter 2.1 --- Introduction --- p.29 / Chapter 2.1.1. --- A General Review of Group 2 Metal Complexes containing Bis(l-Aza-Allyl) Ligands --- p.29 / Chapter 2.1.2. --- A General Review of Group 12 Metal Complexes containing Bis(l-Aza-Allyl) Ligands --- p.32 / Chapter 2.2 --- Results and Discussion --- p.34 / Chapter 2.2.1. --- Preparation and Characterization of Pyrazyl-Linked Bis(l-Aza-Allyl) Di-Magnesium Complex --- p.34 / Chapter 2.2.1.1. --- "Preparation of Pyrazyl-Linked Bis(l-Aza-Allyl) Di-Magnesium Complex [Mg2{{N(SiMe3)C(But)C(H)}2C4H2N2-2,3}Br2(THF)4] (4).……" --- p.34 / Chapter 2.2.1.2. --- Physical and Spectroscopic Properties of Complex 4 --- p.34 / Chapter 2.2.1.3. --- Molecular Structure of Complex 4 --- p.35 / Chapter 2.2.2. --- Preparation and Characterization of Pyrazyl-Linked Bis(l-Aza-Allyl) Lithium Zincate Complex --- p.38 / Chapter 2.2.2.1. --- "Preparation of Pyrazyl-Linked Bis(l-Aza-Allyl) Lithium Zincate Complex [Zn2{{N(SiMe3)C(But)C(H)}2C4H2N2-2,3}Cl2(u-Cl)2Li2(THF)6] (5)" --- p.38 / Chapter 2.2.2.2. --- Physical and Spectroscopic Properties of Complex 5 --- p.39 / Chapter 2.2.2.3. --- Molecular Structure of Complex 5 --- p.39 / Chapter 2.2.3. --- Preparation and Characterization of Unexpected Cyclization Compound --- p.42 / Chapter 2.2.3.1. --- "Preparation of Unexpected Cyclization Compound [{Me2Si{NC(But)C(H)}}2C4H2N2-2,3] (6)" --- p.42 / Chapter 2.2.3.2. --- Physical and Spectroscopic Properties of Complex 6 --- p.43 / Chapter 2.2.3.3. --- Molecular Structure of Complex 6 --- p.44 / Chapter 2.2.4. --- Attempted Synthesis of Analogous Mercury Complex --- p.45 / Chapter 2.2.5. --- Comparison on Structures and Reactivities of Compounds 4-6 --- p.46 / Chapter 2.3. --- Experimental Section --- p.48 / Chapter 2.4. --- References --- p.50 / Chapter CHAPTER 3 --- Syntheses and Characterizations of Bis(Phosphoranoimido) Magnesium and Group 14 Metal Complexes / Chapter 3.1 --- Introduction --- p.52 / Chapter 3.1.1. --- A General Review of Functionalized Phosphoranoimine Ligands --- p.52 / Chapter 3.1.2. --- A General Review of Group 14 Metal Complexes Containing Bis(Phosphoranoimines) Ligands --- p.59 / Chapter 3.2. --- Objective --- p.61 / Chapter 3.3. --- Results and Discussion --- p.64 / Chapter 3.3.1. --- Preparation and Characterization of Bis(Phosphoranoimido) Magnesium Complexes --- p.64 / Chapter 3.3.1.1. --- "Preparation and Characterization of Bis(Phosphoranoimido) Magnesium Complexes [Mg{(Me3SiN=PR2CH)2C5H3N-2,6}THF] (R = Pri, 9; R = Ph, 10)" --- p.64 / Chapter 3.3.1.2. --- Physical and Spectroscopic Properties of Complexes 9 and 10 --- p.64 / Chapter 3.3.1.3. --- Molecular Structures of Complexes 9 and 10 --- p.65 / Chapter 3.3.2. --- Preparation and Characterization of Bis(Phosphoranoimido) Tin(II) and Lead(II) Complexes --- p.70 / Chapter 3.3.2.1. --- "Preparations and Characterizations of 1,3-Distannacyclobutane with Chlorotin(II) Alkyl Complex [{2-{Sn{C(Pri2P=NSiMe3)}}-6- {Sn{CH(Pri2p=NSiMe3)}Cl}}C5H3N]2 (11) and 1,3-Diplumbacyclobutane with bis(trimethylsilyI)amido Lead(II) Alkyl Complex [{2-{Pb{C(Pri2P=NSiMe3)}}-6-{Pb{CH(Pri2P=NSiMe3)}N(SiMe3)2}}- C5H3N]2 (12)" --- p.70 / Chapter 3.3.2.2. --- Physical and Spectroscopic Properties of Complexes 11 and 12 --- p.73 / Chapter 3.3.2.3. --- Molecular Structures of Complexes 11 and 12 --- p.74 / Chapter 3.3.3. --- Preparation and Characterization of Bis(Phosphoranoimido) Germanium(II) Enamido and Alkyl Complex --- p.79 / Chapter 3.3.3.1. --- Preparation and Characterization of Bis(Phosphoranoimido) Germanium(II) Enamido and Alkyl Complex [{2-CH(Pri2P=NSiMe3)-6-CH(Pri2P=NSiMe3)}C5H3NGe{2-{C(Pri2P=NSi Me3)Ge} -6-CH2(Pri2P=NSiMe3)} C5H3N] (13) --- p.79 / Chapter 3.3.3.2. --- Physical and Spectroscopic Properties of Complex 13 --- p.81 / Chapter 3.3.3.3. --- Molecular Structure of Complex 13 --- p.81 / Chapter 3.3.4. --- Comparison on Structures and Reactivities of Compounds 11-13 --- p.85 / Chapter 3.4. --- Experimental Section --- p.87 / Chapter 3.5. --- References --- p.91 / APPENDIX I / Chapter A --- General Experimental Procedures and Physical Measurement --- p.95 / Chapter B --- X-Ray Crystallography --- p.96 / APPENDIX II / Tables of Crystallographic Data and Refinement Parameters --- p.98

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The reactions between the lanthanide nitrate salts and the ligand triphenylphosphine oxide (TPPO) gave rise to nine-coordinated complexes of the nature Ln(TPPO)3(NO3)3, for Ln = La – Dy, Er, Tm, in which the Ln(III) centre is coordinated to three phosphoryl oxygen atoms and three bidentate nitrate ligands. Generally, the geometry can be described as being mer-octahedral, where the nitrate ligands are considered as monoatomic species. The product of the reaction between Yb(NO3)3·5H2O and TPPO, however, was a highly symmetrical eight-coordinated complex, in which the Yb(III) centre was coordinated to two bidentate nitrate groups and four TPPO molecules. The geometry in this case is best described as being trans-octahedral, with the two nitrate ligands coordinated practically perpendicular to one another. The complexes isolated from the reactions of lanthanide nitrate salts with the ligand bis(pentamethylene)urea (PMU) had the general formula Ln(PMU)3(NO3)3, where Ln = La – Dy, Yb, Lu. The complexes were found to be nine-coordinated with distorted trigonal prismatic geometry, in which the one base of the prism is composed of the oxygen atoms of the three PMU ligands and the other base is made up by one oxygen atom from each of the bidentate nitrate groups. The second oxygen atoms of each of the nitrate groups protrude upward, occupying capping positions. The reactions of the La and Pr nitrate salts with the ligand 2,2’-dipyridyl-N,N’-dioxide (DPDO) produced two novel complexes of the nature [Ln(DPDO)(H2O)2(NO3)3]. These complexes are remarkable in that their crystal structures reveal the Ln(III) centres to be ten-coordinated. The geometry around the Ln(III) centres was complex, due to the presence of a seven-membered chelate ring, formed by the bidentate coordination of the oxygen atoms from the DPDO ligands to the metal centres. The chelate ring did not lie in a single plane, but was twisted at the pyridyl bridgeheads to lie above and below the coordination plane.

The extraction of the Rare Earths from two kilograms of Lindsay Light and Chemical Company's "monazite residues" (hydrated Rare Earth oxides), from two kilograms of Norwegian gadolinite, and from five kilograms of Lindsay's "didymium carbonate" (Code 411) gave a mixture of Rare Earths which, after purification, fractional crystallisation as the double magnesium nitrates and ion exchange separation, showed some evidence for the existence of naturally occurring element number 610. This evidence took the form of unexplained lines in the arc spectra, anomalous absorption bands, aid an unexplained peak in the elution curve obtained from the ion exchange work. The evidence presented is far from conclusive and the suggestion is made that further research along these lines be carried out. / Science, Faculty of / Chemistry, Department of / Graduate

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A thesis submitted to the Faculty of Science, University of the Witwatersrand, Johannesburg, in fulfilment of requirements of the requirements for the degree of Doctor of Philosophy. Johannesburg, 2014. / Boron nitride (BN) in its cubic form (cubic boron nitride (c-BN)) is one of the known superhard materials with superior mechanical, chemical and electronic properties. These properties have made it an excellent material in many modern industrial and electronic applications and as such, extensive research grounds have been developed for over half a decade now with the aim of finding alternative ways to synthesize it. The work presented in this thesis was inspired by the fact that defects introduced into the hexagonal form of boron nitride (h-BN) under certain conditions can lead to a change in its local structure and hence the formation of the cubic BN symmetry. The work focused on the introduction of different ions which included helium, lithium, boron, nitrogen and argon into h-BN, by the ion implantation process, in order to promote a defect-induced phase change to the cubic symmetry and possibly to other BN polymorphs. We introduced these ions at different fluences (number of ions per unit area) and energies so as to investigate the best conditions that will influence the lowest activation energy that will in turn favour the c-BN formation. The resulting thin hard layer could be an excellent sub-surface treatment. All the samples used were high quality polycrystalline and single crystal h-BN, obtained from various manufacturers. The fluence range used was from 1×1013 ions/cm2 to 5×1016 ions/cm2, with energy ranging from 40 keV to 150 keV. This energy and fluence choice was inspired by previous research that had been done at higher energies (MeV range) and recommended that low energy (keV range) and fluence could induce similar change. To investigate these effects, various analysis techniques were employed. The major techniques involved optical vibrational methods using Raman Spectroscopy ii iii (RS) and Fourier Transform Infrared Spectroscopy (FTIR) carried out on the samples before and after implantation. Other techniques used included Glancing Incidence X-ray Diffraction (GIXRD), Transmission Electron Microscopy (TEM), and Energy Dispersive X-ray Spectroscopy (EDS). Raman and FTIR measurements showed the introduction of new phonon and vibrational modes in the samples after implantation. The position, size and broadening suggested that they originated from a symmetry attributed to nano-structured cubic BN (nc-BN). The nature and extent of the nc-BN features was very dependent on the implantation parameters with different atomic mass ions each having an optimum fluence with regards to the intensities of the Raman and FTIR signal associated with them. Glancing incidence X-ray diffraction showed new diffraction patterns whose angles corresponded to the cubic and rhombohedral BN symmetries. The linewidths of these peaks were used to estimate the crystal size, which were in the nanoscale range, hence complementing the results obtained by optical spectroscopy. The High-Angle Annular Dark-field Scanning Transmission Electron microscopy (HAADF-STEM) analyses showed regions with low contrast within the implanted region, suggesting that there were regions within the implanted layer that contained dense structures which were attributed to the cubic BN symmetry. Computer simulations using the Stopping and Range of Ions in Matter (SRIM) programme were performed to understand the events that take place during the interaction of the ions with h-BN. Phonon confinement model calculations were also performed to understand the nature of peaks forming after implantation with an aim of support Raman measurements and to estimate the size of the nc-BN domains. With these complementary analyses, it was concluded that indeed implantation is an effective method of creating nanocrystalline c-BN under less extreme conditions of pressure and temperature.

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Thesis (Ph. D.)--Joint Program in Oceanography (Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences; and the Woods Hole Oceanographic Institution), 2005. / Includes bibliographical references (p. 131-149).