Thesis (Ph. D.)--University of Wisconsin, 1966. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliography.

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Kyoto University (京都大学) / 0048 / 新制・論文博士 / 博士(工学) / 乙第12290号 / 論工博第4006号 / 新制||工||1450(附属図書館) / 26628 / UT51-2008-T61 / (主査)教授 檜山 爲次郎, 教授 松原 誠二郎, 教授 中條 善樹 / 学位規則第4条第2項該当

A general broad line nuclear magnetic resonance study was made of the ¹⁹F spectra of WF₆ and the adducts IF₇ • AsF₅ and SF₄ • AsF₅ to determine the temperature dependence of the spectra, interpret the line shapes with respect to isotropic and anisotropic chemical shifts and identify non-equivalent fluorine sites in the compounds. The temperature dependence of the second moment at 30 MHz indicated that rigid lattice conditions probably existed at 77°K for WF₆ and IF₇ • AsF₅ but not for SF₄ • AsF₅. The dependence indicated an nmr transition in the vicinity of 200°K for the first two compounds and one commencing below 77°K for the third. From the second moments in the vicinity of the transitions, activation energies mere determined for the average motions involved. The field dependence of the second moments of the compounds was examined, where possible, at 2, 16, 30, 40, 56.4, and 94.1 MHz at 77° and 295°K. The compounds' spectra were resolved, with varying degrees of success, into components. For WF₆ an approximate resolution could be made into two components corresponding to the four equatorial and two axial fluorines in the distorted octahedron at 77°K. The two adducts could both be resolved, especially at 295°K or above, into components which supported the ionic formulations IF⁺₆ AsF⁻₆ and SF⁺₃ AsF⁻₆. Non-equivalent fluorine sites within individual ions could not be detected. From the observed and estimated second moments of the resolved components above and below the transitions, the probable reorientations occuring above the transitions were suggested. The rigid lattice theoretical second moment calculations enabled suggestions to be made for the crystal structures of WF₅ and SF⁺₃AsF⁻₆ and for the bond lengths in IF⁺₆AsF⁻₆ . For the first there had been confusion, at least here, about the space group, while the second has not yet been the subject of reported X-ray studies. Axial symmetry of the chemical shift tensors was assumed. Then, taking account of the relative shifts between the resolved components, averaqe values of the chemical shift anisotropies for each of WF₆ and IF⁺₆ AsF⁻₆ were determined from expressions relating the field squared dependence of the second moment to those quantities. The mean isotropic shifts of the total F spectra for each compound were measured where possible at each field at 77° and 295° K with respect to CF₃. COOH. From those the shifts of the resolved components were calculated relative to HF. Then from the isotropic shifts and the anisotropies, the principal values of the axially symmetric shift tensors were determined. The principal values enabled estimates to be made of I (ionic) and ℓ(double bond) characters, neglecting hybridization, in the M-F bonds of the hexafluoride groups. From these values a prediction was made for I and ℓ in the axial and equatorial bonds in PuF₆ . / Science, Faculty of / Chemistry, Department of / Graduate

The work reported here is: 1) a detailed study of the ¹⁹F nuclear magnetic resonance (n.m.r.) spectra of KPO₂F₂. The temperature dependence of the second moment and line width is interpreted in terms of reorientation of the PO₂F₂⁻ anion in the crystal lattice. A detailed analysis of the line shape at low temperatures is used to yield the interatomic spacings of the PF₂ fragment in the PO₂F₂⁻ anion. 2) an investigation of the n.m.r. adiabatic rapid passage technique as a quick and simple method for determining nuclear Zeeman spin-lattice relaxation times, T₁. The limitations of the experiment are examined and correction formulae are presented. The temperature dependence of T₁ is observed for the globular molecules, exo- and endo-pentadienyl maleic anhydride, for the fatty acid soap, lithium stearate, and for the inorganic salt, KPO₂F₂. The data are interpreted to yield some of the kinetics of molecular motion in these solids. 3) a ¹⁹F nuclear magnetic resonance investigation of polycrystalline K₂NbF₇ and K₂TaF₇, yielding some of the kinetics of molecular motion. The crystal structures, as seen by n.m.r., are found to be essentially identical. 4) an investigation of the ¹⁹F n.m.r. spectra of paramagnetic RhF₅. and IrF₅. This study has been reasonably successful in elucidating the molecular configuration of these substances, a problem uniquely suitable to the n.m.r. technique and insoluble to most other methods of structural analysis. The very large resonance shifts are interpreted in terms of unpaired electron density at the fluorine atoms. 5) a brief examination of the electron spin resonance spectra of X-irradiated polycrystalline KPO₂F₂ and Na₂PO₃F. Two anion radicals, PO₃⁼ and PO₂F⁻ , are identified and, within certain approximations, the nearly isotropic hyperfine coupling constants are evaluated and interpreted in terms of unpaired electron spin densities at the magnetic nuclei. Presentation of Data The organization of this dissertation differs from the form usually found. The justification offered in its behalf is that the topics covered can more easily be listed in a horizontal rather than a vertical array. Therefore, the presentation, theoretical comparison and discussion of the data have been grouped together for each topic. The order in which topics are considered depends on their priority in common discussion and their interdependences. The first to be considered is the n.m.r. line shape of the fluorine resonance in KPO₂F₂. Then, using experimental results as a guide, a determination of the interatomic distances is attempted. The temperature dependences of the n.m.r. line shape is presented and a model describing the type of molecular motion is sought. An explanation of the adiabatic rapid passage technique is then considered because it is used to obtain the spin-lattice relaxation time data. The spin-lattice relaxation time data of ¹⁹F in CaF₂ and KPO₂F₂ and of the ¹H in lithium stearate and endo- and exo-pentadienyl maleic anhydride are then considered. The limits of applicability of the adiabatic rapid passage technique are considered. The n.m.r. line shape of the fluorine resonance in K₂NbF₇ and K₂TaF₇ and its variation with temperature are interpreted in terms of molecular motion. A modified line width-correlation frequency equation first derived by Bloembergen, Purcell and Pound is used to derive an activation energy describing the hindered reorientation of the NbF₇⁼ and TaF₇⁼ anions in the low temperature solids. The n.m.r. line shape of the fluorine resonance in IrF₅- and RhF₅ is used to elucidate the molecular structure, a problem uniquely suitable to n.m.r. The large resonance shifts of the fluorine resonances may be used to obtain the unpaired electron density at the fluorine nuclei. The e.s.r. line shape observed for X-irradiated polycrystalline KPO₂F₂ and Na₂PO₃F is interpreted in terms of the •PO₂F⁻ and the •PO₃⁼ radicals, respectively. The hyperfine coupling constants are obtained and the electron density at the phosphorous and fluorine atoms are estimated. / Science, Faculty of / Chemistry, Department of / Graduate

The research described in this Thesis investigates the coordination chemistry of pentafluorooxotellurate(VI) (F5TeO– or “teflate”) and [PnF6]– (Pn = As, F) derivatives of mercury(II), and expands the chemistry of Ng(II) (Ng = Kr, Xe) by characterizing several NgF2 coordination complexes with mercury, and the synthesis of a new xenon(II) oxide cation. The compounds discussed herein were characterized predominately by low-temperature single-crystal X-ray diffraction and Raman spectroscopy, and were frequently complemented by quantum-chemical calculations. The chemistry of the F5TeO–group was developed for Hg(II) derivatives by investigating the Lewis acid properties of Hg(OTeF5)2. Initial efforts investigated interactions with the nitrogen base NSF3, and resulted in the coordination complexes [Hg(OTeF5)2∙N≡SF3]∞, [Hg(OTeF5)2∙2N≡SF3]2, and Hg3(OTeF5)6∙4N≡SF3 at 0oC. Although the F5TeO–group often bonds in a monodendate fashion, these less sterically saturated salts result in oxygen bridging in the solid state. In Hg3(OTeF5)6∙4N≡SF3, oxygen bridging between three metal centers by the pentafluorooxotellurate(VI) group is observed for the first time. The nature of this new bonding was further analysed computationally for Hg3(OTeF5)6∙4N≡SF3 by natural bond orbital analyses (NBO). At room temperature, reactions of Hg(OTeF5)2 with NSF3 resulted in O/F metatheses to yield related F2OSN–derivatives, namely [Hg(OTeF5)(N=SOF2)∙N≡SF3]∞ and [Hg3(OTeF5)5(N=SOF2)-∙2N≡SF3]2, accompanied by the elimination of TeF6 as confirmed by 19F NMR spectroscopy. In related work, the acceptor properties of Hg(OTeF5)2 were further investigated in its reactions with M[OTeF5] (M = [N(CH3)4]+, [N(CH2CH3)4]+, Cs+) to form a series of teflate anion salts; [N(CH2CH3)4]2[Hg(OTeF5)4], [N(CH3)4]3[Hg(OTeF5)5], [N(CH2CH3)4]3[Hg(OTeF5)5], [N(CH3)4]2[Hg2(OTeF5)6], Cs2[Hg(OTeF5)4]•Hg(OTeF5)2, and {Cs3[Hg2(OTeF5)7]•Hg(OTeF5)2}•4SO2ClF. In comparison to their halide counterparts, the less basic and more sterically demanding teflate ligands of the Hg(II) anions show less tendency to extensively bridge. The Raman spectra of the [Hg(OTeF5)4]2−, [Hg(OTeF5)5]3−, and [Hg2(OTeF5)6]2− anions were fully assigned with the aid of their calculated gas-phase vibrational frequencies. NBO analyses further probed the bonding in the anions. The [Hg(OTeF5)5]3− anion provides an unusual square-pyramidal coordination sphere around mercury and the only presently known teflate-substituted anion with a net charge of 3–. In related work, the weakly coordination anion (WCA) [Sb(OTeF5)6]– was substituted in Hg2+ salts using weakly coordinating SO2ClF solvent to give the homoleptic solvent complex, [Hg(SO2ClF)6][Sb(OTeF5)6]2. The ability of this salt to function as a precursor for other ligands was demonstrated by the reaction with the nitrogen bases NCR (R = –CH3 or –CH2CH3) which resulted in the isolation and full characterization of the corresponding homoleptic nitrile complexes [Hg(NCR)5][Sb(OTeF5)6]2ꞏ2SO2ClF. Gas-phase energy-minimized calculation of the cations aided in the vibrational assignment of the Raman spectra, whereas NBO and counterpoise corrected binding energies give insights into the strength of the metal-ligand bonds and resulting electronic effects of these interactions. The established Lewis acidity of Hg(OTeF5)2, and known oxidative resistance of the F5TeO–group, were exploited to form rare examples of noble-gas difluoride adducts, Hg(OTeF5)2•1.5NgF2 (Ng = Xe, Kr). The isostructural complexes were fully characterized, and the KrF2 adduct provided only the second crystallographically characterized KrF2 complex and the first example of bridge coordination by KrF2¬. The chemistry of krypton was significantly extended by further exploring the little studied coordination of KrF2 with the salts Hg(PnF6)2 (Pn = As, Sb) and FHg(AsF6), leading to an important series of coordination complexes. The first homoleptic KrF2 coordination complex, [Hg(KrF2)8][AsF6]2•2HF, was thoroughly characterized by single-crystal X-ray diffraction, Raman spectroscopy, and quantum-chemical analyses. It provides the highest KrF2-to-metal ratio that is currently known for a coordination complex. The bonding was extensively analysed by NBO, calculated binding energies, energy decomposition analyses (EDA), and Extended Transition State Natural Orbitals for Chemical Valence (ETS-NOCV) analyses. This computational work suggests that both orbital interactions, which incorporate covalent bonding, and electrostatic contributions are important stabilization factors and that the 8σg (HOMO‒4) orbital and, to a lesser extent, a degenerate 4πu (HOMO) orbital, derived from free KrF2 (D∞h) are involved in adduct formation. This result helps to rationalize the observed M---F–Kr(F) coordination angles observed for most terminally coordinated NgF2 complexes. A series of related complexes with one to five KrF2 molecules per metal center were also characterized by single-crystal X-ray diffraction, namely Hg(KrF2)(HF)(AsF6)2 (1), Hg(KrF2)2(AsF6)2 (2), Hg(KrF2)3(HF)(SbF6)2 (3), [Hg(KrF2)4(HF)2(SbF6)]2[SbF6]2 (4), Hg(KrF2)5(AsF6)2 (5), Hg(KrF2)4(HF)2(AsF6)2•HF (6), FHg(μ3-FKrF)1.5(KrF2)0.5(AsF6) (7), and FHg(μ3-FKrF)0.5(KrF2)1.5(AsF6) (8). These complexes were unambiguously characterized by single-crystal X-ray diffraction which showed that the structures became more extensively linked due to bridging between mercury and the [PnF6]‒ anions as the number of coordinated KrF2 ligands decreased. While compounds (1)-(6) solely contain terminally coordinated KrF2 ligands, compound (7) also contains the second structurally characterized example of KrF2 bridging two metal centers through each of its fluorine atoms. Replacement of [AsF6]‒ by F‒ in compounds (7) and (8) also resulted in the first examples of a new bonding modality of KrF2, where only one of the fluorine atoms bridges two different metal centers. The Raman spectrum of (5) was assigned with the aid of calculated gas-phase vibrational frequencies. Natural bond orbital (NBO) analyses of [Hg(KrF2)5][AsF6]2 are consistent with coordinate covalent ligand-metal interactions. The nature of bonding for the unprecedented KrF2 bonding modality was further probed computationally with EDA and ETS-NOCV analyses and corroborate an MO description where electron density is donated from both the 8σg (HOMO‒4) and a degenerate 4πu (HOMO) molecular orbital of KrF2 to LUMOs involving the 6s and 6p orbitals of each mercury atom. To further expand the chemistry of the noble-gases, the second known xenon(II) oxide, [XeOXe]2+, was synthesized from the reaction of [FXeOXe---FXeF][AsF6] and acetonitrile at low-temperatures in anhydrous HF. The cation was isolated in macroscopic quantities as its well-isolated adduct-dication [CH3CN---XeOXe---NCCH3][AsF6]2 salt and was fully characterized by single-crystal X-ray diffraction and 16/18O isotopic enrichment Raman studies. The [XeOXe]2+ adduct-cation provides an important example of σ-hole bonding by a nitrogen base to a Xe(II) atom. The nature and strength of the Xe–O and Xe–N bonds in the calculated gas-phase [XeOXe]2+ and [CH3CN---XeOXe---NCCH3]2+ cations were extensively explored using a range of quantum-chemical (QC) methods, namely, NBO, atoms in molecules (AIM), electron localization function (ELF), and molecular electrostatic potential surface (MEPS) analyses. / Thesis / Doctor of Philosophy (PhD) / The coordination chemistry of pentafluorooxotellurate(VI) (F5TeO– or “teflate”) derivatives, as well as [PnF6]– (Pn = As, Sb) salts, of mercury(II), and the chemistry of Ng(II) (Ng = Kr, Xe), are the major focuses of this Thesis. The Lewis acid properties of Hg(OTeF5)2 were investigated using the nitrogen base, NSF3, and M[OTeF5] salts (M = Cs+, N(CH3)4+, N(CH2CH3)4+) which resulted in a series of NSF3 adducts, F2S(O)N– derivatives, and several anions. Reactions of Hg(OTeF5)2 with NgF2 also provided rare examples of bridging NgF2 coordination complexes. Routes to [Sb(OTeF5)6]– salts containing weakly-solvated Hg2+ cations was developed, which provided an important synthetic precursor to explore further ligand substitution reactions at Hg2+. The relatively unexplored chemistry of krypton was further advanced by synthesizing a series of coordination complexes of KrF2 with Hg(PnF6)2 and FHg(AsF6) salts, providing rare examples of terminally coordinated and bridging KrF2 ligands, and a new coordination mode for KrF2 molecules. Advances in the chemistry of Xe(II) were also made through the synthesis and characterization of the second known, and simplest, xenon(II) oxide species. Characterization methods employed in this Thesis predominantly were single-crystal X-ray diffraction and Raman spectroscopy. Quantum-chemical calculations aided with Raman assignments, and were used to further investigate the nature of chemical bonding in the compounds that had been synthesized. The research described in this Thesis significantly contributes to and extends the chemistry of the pentafluorooxotellurate(VI) ligand, to our knowledge and understanding of the reactivity and bonding of krypton(II) and xenon(II) species, and most notably, the coordination chemistry of KrF2.

Chapter 1 introduces the discovery of elemental fluorine by H. Moissan and some uses of inorganic fluoride. Organo fluoro compounds and their place in pharmaceuticals and agrochemicals are also introduced. The general properties of fluorine and the C-F bond are discussed as well as conformational influences such as the fluorine gauche effect. Chapter 2 describes the C-N⁺------F-C charge dipole interactions within protonated amines and explains the influence of a β fluorine on the conformation on various crystalline structures. A number of systems are synthesised which contain this charge dipole interaction, such as four, five and eight membered aza heterocycles. It was demonstrated that these provided a N⁺-C-C-F gauche torsion angle. This electrostatic effect was also observed in the non-protonated N-ethylpyridinium cations possessing a fluorine β to the charged nitrogen. This clearly showed that hydrogen bonding is not playing a part in the observed N⁺-C-C-F gauche interactions and that it is a purely electrostatic effect. Chapter 3 discusses the effort to explore the C-O⁺-------F-C charge dipole interaction and the synthetic approaches that were taken towards candidate substances. However in the event a Grignard reaction on a fluoro cyclohexanone was found to provide an unexpected product where rearrangement followed by fluorine elimination had occurred. Chapter 4 details the experimental procedures for the compounds synthesised in this thesis and an Appendix outlines the detail of 24 crystal structures that were solved during this research.

The measurement of fluorine penetration into archeological flint artifacts using Nuclear Reaction Analysis (NRA) has been reported to be a potential dating method. However, the mechanism of how fluorine is incorporated into the flint surface, and finally transported into the bulk is not well understood. This research focuses on the study of the fluorine uptake phenomenon of flint mineral in aqueous fluoride solutions. Both theoretical and experimental approaches have been carried out. In a theoretical approach, a pipe-diffusion model was used to simulate the complicated fluorine transportation problem in flint, in which several diffusion mechanisms may be involved.

Call number: LD2668 .T4 1978 K86 / Master of Science