The tetra-halides of zirconium and hafnium were reacted with one equivalent of the potentially tridentate hybrid ligand, N(SiMe₂CH₂PR₂)2-, (R = Me, i-Pr, t-Bu) to generate the corresponding mono-ligand complexes MCl₃{N(SiMe₂CH₂PR₂)₂), (M = Zr, Hf). Based on the results obtained from the solution spectroscopic data and the single crystal X-ray diffraction analyses of HfCI₃{N(SiMe₂CH₂PMe₂)₂> and ZrCl₃{N(SiMe₂CH₂P(i-Pr)₂)₂) the stereochemistries of all the MCI ₃{N(SiMe ₂CH₂PR₂) ₂) complexes were found to be meridional in solution, but both facial and meridional geometries were displayed in the solid state dependent on the ligand. The mono-ligand derivatives served as useful starting materials for the generation of zirconium- and hafnium-carbon bonds. Thus the addition of three equivalents of MeMgCl to one equivalent of MCl₃{N(SiMe₂CH₂PR₂)₂} generated the trimethyl complexes M(CH₃)₃{N(SiMe₂CH₂PR₂)₂}. When two equivalents of MeMgCl was added to the mono-ligand complexes, an inseparable mixture of the monomethyl and dimethyl derivatives was obtained. The stereochemistry of Hf(CH₃)₃{N(SiMe₂CH₂PMe₂)₂} is facial in the solid state but displays unusual fluxional behaviour in solution. This behaviour is observed for all the trimethyl derivatives as a consequence of the dissociative nature of the phosphine donors. Several possible rearrangement pathways for these compounds are discussed in an attempt to interpret this behaviour in solution. / Science, Faculty of / Chemistry, Department of / Graduate

The long-term goal of this research project is the development of solution-based inorganic dielectric and semiconductor materials for inkjet printed electronics. The main focus of this thesis involves testing of the materials and devices under development. A new solution-based inorganic dielectric material (HfOSO₄), given the name hafsox, is developed and shows excellent dielectric properties. Hafsox with the addition of lanthanum, to improve film dehydration, has successfully been demonstrated as a gate dielectric. Metal-insulator-metal (MIM) capacitance testing of hafsox with lanthanum, has resulted in a low loss tangent of 0.30% at 1 kHz, a relative permittivity of 11.47 at 1 kHz, a breakdown voltage of 6.30 MV cm⁻¹, and a leakage current density of 4.38 nA cm⁻² at 1 MV cm⁻¹. Progress has also been achieved in the development of solution-based semiconductor materials. To date the most successful of these materials is zinc indium oxide (ZIO), which has been demonstrated as a thin-film-transistor (TFT) channel material. This ZIO TFT is a depletion-mode device with a turn-on-voltage of V[subscript on]~ -19 V, a threshold voltage of V[subscript T] ~-16 V, and a drain current on-to-off ratio of ~10³. Mobilities extracted from this ZIO TFT include an incremental mobility of μ[subscript inc] ~0.05 cm² V⁻' sec⁻', an effective mobility of μ[subscript eff] ~0.02 cm² V⁻' sec⁻', and an average mobility of μ[subscript avg] ~0.02 cm² V⁻' sec⁻' at V[subscript GS]=20 V. The development of metal-semiconductor field-effect transistors (MESFET) TFTs is also investigated as a means of eliminating the need for a dielectric material in order to reduce the complexity of fabricating circuits. MESFETs are attempted with semiconductor materials such as CdS that is deposited by chemical bath deposition (CBD) and SnO₂ that is deposited by RF magnetron sputtering, but with little success. The most successful MESFET-like device fabricated, employing SnO₂ as the channel material, is a strong depletion-mode device with a small amount of gate voltage modulation. / Graduation date: 2006

The chemistry of hafnium oxide based and materials are described in the context of ion exchange and lithography. HafSOx, represented by the composition HfO₂₋[subscript x](SO₄)x, is described to possess a significant capacity towards ion exchange in acidic and basic solutions, enabling films of HafSOx to be cleanly and readily be converted to oxide films by neutralization. The optical properties, composition and morphology of these oxide films are characterized. The fabrication of mixed metal oxide films is demonstrated via solution and ion exchange routes. This thesis also explores the photoresist chemistry of HafSOx resists. A photoreaction mechanism based on the decomposition of peroxide is proposed. In addition, the patterning of HafSOx films by 193 nm, extreme ultraviolet (EUV) and electron beam radiation is described, and the influence of composition on its photoresist properties is studied. / Graduation date: 2012

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This thesis describes the synthesis and characterisation of new mononuclear and binuclear zirconium and hafnium compounds containing ansa-bridged ligands. Some olefin polymerization studies, employing the new compounds as catalysts, are also presented. <strong>Chapter 1</strong> begins with an introduction to Ziegler-Natta polymerization of olefins, concentrating on recently developed metallocene-based catalyst systems. The second part of the Chapter charts the development of group 4 ansa-metallocene derivatives, especially their use as stereospecific catalysts. Finally, a review of binuciear group 4 metallocene compounds containing bridging bis(cyclopentadienyl)-type ligands is presented. <strong>Chapter 2</strong> describes the synthesis and characterisation of some novel mononuclear metallocene compounds of zirconium and hafnium containing ansa-bridged ligands. The ansa-bridged mononuclear compounds [{Me₂C(η⁵-C₅H₄)(η²-C₉H₆)}M(η⁵C₅H₅)Cl] (M = Zr, Hf), [{(CH₂)₅C(η⁵-C₅H₄)(η²-C₉H₆)}M(η⁵-C₅H₅)Cl] (M = Zr, Hf) and [{Me₂(η⁵-C₅H₄)(η³-C₁₃H₈)}Zr(η⁵-C₅H₅)Cl] are described, along with the X-ray crystal structures of the zirconium compounds. The η²-indenyl and η³-fluorenyl coordination modes observed for these compounds are unprecedented. The synthesis and characterisation of the novel, mononuclear ansa-bridged compounds [{Me₂C(η⁵-C₅H₄)<sub<2</sub>}M(η⁵-C₅H₅)Cl] (M = Zr, Hf) is also described, along with their X-ray crystal structures. The variable temperature solid state ¹³C CP/MAS NMR spectra of [{Me₂C(η⁵-C₅H₄)<sub<2</sub>}M(η⁵-C₅H₅)Cl] (M = Zr, Hf) show slow rotation of the C₅H₅ ring on the NMR timescale. <strong>Chapter 3</strong> describes the synthesis and characterisation of some novel homo- and hetero-binuclear metallocene compounds of zirconium and hafnium in which the metals are bridged by an unsymmetrical ansa ligand. The novel, chiral homobinuclear compounds [(η⁵-C₅H₅)MCl₂{(η⁵-C₅H₄)CMe₂(η⁵-C₉H₆)}MCl₂(η⁵-C₅H₅)] (M = Zr, Hf) are described. The ansa-bridged mononuclear compounds [{Me₂C(η⁵-C₅H₄)(η²-C₉H₇)M(η⁵-C₅H₅)Cl] (M = Zr, Hf) are used as reagents for the selective synthesis of the heterobinuclear analogues [(η⁵-C₅H₅)MCl₂{(η⁵-C₅H₄)CMe₂(η⁵-C₉H₆)}M*Cl₂(η⁵-C₅H₅)] (M = Zr, M* = Hf ; M = Hf, M* = Zr) and the unsymmetrical homobinuclear compound [(η⁵-C₅H₅)ZrCl₂{(η⁵-C₅H₄)CMe₂(��⁵-C₉H₆)}ZrCl₂(η⁵-C₅Me₅)]. The methylated derivatives [(η⁵-C₅H₅)M(CH₃)₂{(η⁵-C₅H₄)CMe₂(η⁵-C₅H₆)}M*(CH₃)₂(η⁵-C₅H₅)] (M = Zr, M* = Zr, Hf; M = Hf, M* = Zr, Hf) are also described. The structurally related mononuclear compounds [(η⁵-C₅H₅)MCl₂{(η⁵-C₅H₄)CMe₂(C₉H₇)}] (M = Zr, Hf) and [(η⁵-C₅H₅)Zr(CH₃)₂{(η⁵-C₅H₄)CMe₂(C₉H₇)}] have also been prepared. <strong>Chapter 4</strong> presents some olefin polymerization studies using the new compounds described in Chapter 3 as catalysts, along with either methylaluminoxane or the recently developed co-catalysts [Ph₃C]⁺[B(C₆F₅)₄]^- and B(C₆F₅)₃. <strong>Chapter 5</strong> provides the experimental details for the reactions described in this thesis and the characterising data for all new compounds are given in <strong>Chapter 6</strong> Crystallographic data for the for the X-ray structure determinations in Chapter 2 are given in the <strong>Appendices</strong>.

Thesis (Ph. D. in Chemical Engineering)--Vanderbilt University, Aug. 2008. / Title from title screen. Includes bibliographical references.

Thesis (Ph. D.)--University of Texas at Austin, 2004. / Supervisor: Jack C. Lee. Vita. Includes bibliographical references. Also available from UMI.

Thesis (Ph. D.)--University of Texas at Austin, 2004. / Supervisor: Jack C. Lee. Vita. Includes bibliographical references.

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