Thesis (Ph. D.)--University of Wisconsin--Madison, 1953. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 82-90).

Thesis (M.S.)--University of Wisconsin--Madison, 1969. / eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

The density, surface tension and viscosity of liquid vanadium pentafluoride have been measured. The high value of the viscosity indicates that the liquid is probably associated in a somewhat similar manner to antimony pentafluoride, thus supporting recent evidence which has suggested that inter-molecular association is also an important process in these associated fluorides The infrared spectrum of vanadium pentafluoride vapor has been measured in the region 250 to 3500 cm- ¹ and the results have been interpreted in terms of a monomeric trigonal bipyramid molecular structure in view of the normal vapor density Vanadium pentafluoride formed a 1:1 complex with selenium tetrafluoride The apparently similar sulphur tetrafluoride complex was extremely unstable Vanadium tetrafluoride is best prepared by fluorinatmg vanadium tetrachloride with anhydrous hydrogen fluoride in trichlorofluoromethane solution Vanadium tetrafluoride disproportionates readily at 100° in vacuum into the trifluoride and the pentafluoride Solid vanadium tetrafluoride also sublimes slowly at 100-120° in vacuum The available structural information suggests that in vanadium tetrafluoride the vanadium atom is surrounded by six fluorine atoms to form an octahedral VF₆ unit Four fluorines are shared with adjacent vanadium atoms thus forming a polymeric fluorine -bridge-bonded structure The infrared spectrum of solid VF₄ has been interpreted in terms of this model Bromine trifluoride and gaseous fluorine readily fluorinated vanadium tetrafluoride to the penta-fluoride In the presence of iodine pentafluoride, nitryl fluoride oxidised vanadium tetrafluoride and formed the nitryl salt NO₂VF₆. Ammonia, pyridine and selenium tetrafluoride formed 1.1 complexes with VF₄ Vanadium tetrafluoride did not react with sulphur tetrafluoride, sulphur trioxide or sulphur dioxide Potassium hexafluorovanadate (IV) was prepared frpm potassium fluoride and vanadium tetrafluoride in selenium tetrafluoride solution. The trigonal form was obtained with lattice constants of a = 5 68, c = 4 66 A. Alkaline earth fluorides did not form hexafluorovanadate salts with vanadium tetrafluoride in iodine pentafluoride KVF₅ could not be prepared from equimolar proportions of potassium fluoride and vanadium tetrafluoride in iodine pentafluoride solution All of the tetravalent vanadium fluoride compounds which have been studied obeyed the Curie-Weiss law, with very high values of the Weiss Constant Separation of antiferromagnetism and spm-orbit interaction is not possible as both effects are likely to arise from the proposed fluorine bridging The heat of hydrolysis of vanadium tetrafluoride in water has been found to be -27 5 kcal /mole, and this value was used in a Hess law calculation to obtain -332 kcal /mole for the heat of formation of vanadium tetrafluoride Vanadium pentafluoride was hydrolysed under similar conditions in a dilute alkali solution and the resultant heat of hydrolysis, -141 kcal /mole, was used to calculate the heat of formation of - 352 kcal /mole for vanadium pentafluoride. Lattice energies were estimated from a simple formula given by Kapustmskii and used in a Born-Haber cycle to calculate heats of formation Using the calculated heat of formation of vanadium trifluoride and the experimental values for vanadium tetrafluoride and vanadium pentafluoride, the spontaneity of the disproportionation of vanadium tetrafluoride was confirmed. The heat of hydrolysis of vanadium tetrachloride in water is -68 8 kcal /mole With this value, the heat of formation of the aqueous vanadyl ion was calculated as -113 kcal /mole / Science, Faculty of / Chemistry, Department of / Graduate

The present investigation was concerned with a study of the preparation and properties of chromium tetrafluoride and its complexes; magnetic properties and X-ray structures were also studied. Attempts to prepare the pentafluoride of chromium using fluorinating agents other than fluorine were unsuccessful. Chromium tetrafluoride was prepared by the action of fluorine on the heated metal, the products being involatile chromium trifluoride, volatile chromium tetrafluoride, and more volatile fluorides which were condensed at -78°C. The best yields of chromium tetrafluoride were obtained at 350°C and with a moderate flow-rate of fluorine. Chromium tetrafluoride is a glassy solid which forms blue vapours when heated. It does not dissolve in the usual organic solvents and is hydrolysed readily in moist air. It is paramagnetic, the moment corresponding to two unpaired electrons, and has a Weiss Constant of -70°. Chemically, chromium tetrafluoride is surprisingly inert and at room temperature does not react with ammonia, pyridine, sulphur dioxide, sulphur trioxide, iodine pentafluoride, bromine trifluoride, bromine pentafluoride, chlorine trifluoride, or selenium tetrafluoride. However, it reacts instantaneously with water, giving Cr⁺³ and CrO₄¯² ions in solution. When heated with bromine trifluoride for longer periods, reaction occurs to give CrF₃.0.5BrF₃. On heating with a mixture of bromine trifluoride and bromine pentafluoride, a wine-coloured solution was obtained, and the residue after distillation of volatile materials was CrOF₃.0.25BrF₃. The reaction of selenium tetraf luoride with chromium tetrafluoride at 120°C yielded two compounds, CrF₃SeF₄ and CrF₂.SeF₄. Complexes of the type ACrF₅, where A = K, Rb, or Cs, were prepared for the first time, by heating the respective alkali metal chloride and chromium tetrafluoride in a 1:1 molar ratio in bromine trifluoride. The resulting complex compounds contained half a molecule of bromine trifluoride per molecule of the complex, if the removal of excess bromine trifluoride, after the reaction, was carried out at 100°C. However, if removal was carried out at 160°C, the pure complexes were obtained. Complexes of the type A₂CrF₆, where A = K or Cs, were prepared in bromine trifluoride solutions. The presence of extra bromine trifluoride in the molecule of the complex compound affected the structure seriously in potassium complexes but had no effect on cesium complexes. Thus K₂CrF₆0.5BrF₃ was tetragonal and on heating at 160°C in, vacuo yielded the cubic modification of pure K₂CrF₆; Cs₂CrF₆.0.5BrF₃and Cs₂CrF₆ were both cubic. Reactions of chromium trioxide with bromine trifluoride, bromine pentafluoride, and chlorine trifluoride were also investigated. With bromine fluorides, the products obtained were the corresponding adducts of CrOF₃. These are very reactive and sensitive to moist air. The compounds are paramagnetic. The reaction with chlorine trifluoride was very interesting because the appearance of the product depended on/ the experimental conditions. If the reaction was carried out at ordinary temperature, the product was a buff-coloured powdery mass, but if the reaction was performed by passing chlorine trifluoride vapour over heated chromium trioxide (100—120°C), the product was a brick-red substance. Chemical analyses and magnetic measurements indicated that both these products were identical and had the composition CrOF₃.0.25ClF₃. The brick-red product could be converted into the light buff-coloured powdery mass by heating at 70°C in vacuo. Reactions of potassium dichromate with bromine trifluoride, bromine pentafluoride, and chlorine trifluoride were also investigated. Potassium dichromate reacted with these smoothly at room temperature and the product of reaction in each case was KCrOF₄. The compounds investigated in the present research are tabulated below.[ Table omitted ] / Science, Faculty of / Chemistry, Department of / Graduate

The preparation and reactions of simple and complex fluorides of palladium and gold using fluoride solvents have been studied. Two new compounds, fluoselenonium hexafluopalladate (IV) and fluoselenonium tetrafluoaurate (III), have been prepared. Both are acids in the selenium tetrafluoride solvent system. Fluoselenonium hexafluopalladate (IV) reacts with a base, potassium pentafluoselenate (IV), to form a salt, potassium hexafluopalladate (IV) which crystallizes in a trigonal modification, a = 5.717 ± .003 Å, c = 4.667 ± .003 Å . Pure palladium difluoride has been produced in two reactions. These reactions are: (1) the thermal decomposition of fluoselenonium hexafluopalladate (IV), and (2) the reduction of palladium trifluoride with selenium tetrafluoride. The magnetic moment of the bromine trifluoride adduct of palladium trifluoride has been measured and found to be 2.2 B.M. Evidence is presented for the existence of a potassium salt of the trifluopalladate (II) ion. It has not been possible to prepare complex fluorides of terpositive palladium in selenium tetrafluoride solution. / Science, Faculty of / Chemistry, Department of / Graduate

The kinetics of the reaction of solid strontium chloride with fluorine gas have been studied by gravimetric, thermometric, and microphotographic methods. ESR and X-ray crystallography were used to study the products. The reaction commenced after an induction period of 1 to 10 minutes. On single crystal specimens studied microscopically, formation and growth of nuclei of SrF₂ thereafter occupied several minutes before the nuclei coalesced to form a continuous SrF₂ layer. By thermometric studies on a polycrystalline boule of reactant on a thermocouple, the extent of reaction during the nucleation period was found to be proportional to t⁴ , suggesting nuclei formed proportional to t² and subsequent two-dimensional growth at constant linear rate. On single crystal specimens, microphotography showed a t² law for number of nuclei only for one specimen with a rough surface. For smooth surfaces, number of nuclei was generally constant, but linear growth was confirmed in many cases. Two growth rates were measured, an initial rate of 6.4 x 10ˉ⁴ mm sec ˉ¹ and a less reproducible rate to which a transition sometimes occurred in later stages of 1.7 x 10ˉ³mm secˉ¹. The nucleation was found to be non-activated and the change in rate was ascribed, together with an increase in the number of nuclei late in the nucleation period, to effects of mechanical strain. The development of the main reaction after establishment of a continuous reaction interface was followed gravimetrically, and found to obey the Ginstling-Brounshtein equation for diffusion through a spherical shell of solid reaction product, having a sharp interface with the reactant. A lower limit of 2 x 10ˉ⁵ cm² secˉ¹ was found for the diffusion coefficient, suggesting that the process is gaseous diffusion in cracks in the product layer. The crystallinity of the product depended on the rate of reaction. For rapid, high-temperature reaction, the product gave a powder diffraction pattern, but for a sample reacted more slowly with a controlled supply of F₂, the product was found to be essentially a single crystal (diffuse diffraction spots indicating ranges of disorientation of no more than about 5°) with the same crystallographic orientation as the reactant. Attempts to locate the ESR signal found in earlier work were only partially successful, but suggest that the signal is largely in the product phase, and that it represents a byproduct rather than a reaction intermediate. / Science, Faculty of / Chemistry, Department of / Graduate

Indiana University-Purdue University Indianapolis (IUPUI)

Indiana University-Purdue University Indianapolis (IUPUI)

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Thesis (M.S.)--University of Louisville, 1996. / School of Dentistry, Program in Oral Biology. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.