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The fluorides and oxyfluorides of osmium and the oxidizing properties of the noble metal hexafluorides

University of British Columbia

An investigation of the attainable oxidation states of osmium in reaction with fluorine and fluorine-oxygen mixtures was carried out. The first simple heptavalent compound of osmium, osmium oxide pentafluoride, OsOF₅, was prepared by the fluorination of anhydrous osmium dioxide. This compound was characterized by analysis, X-ray single crystal and powder methods, and by infrared spectroscopy. The vapour pressure-temperature relationship and derived thermodynamic data have been evaluated. The magnetic susceptibility has been measured over the temperature range 77° to 300°K. The existence of an octavalent osmium oxyfluoride, osmium trioxide difluoride, OsO₃F₂ has been confirmed. This compound is diamagnetic and the solid is dimorphic. Preliminary structural work has indicated that the osmium is six-coordinated in this compound. A related ternary fluoride, NOOsO₃F₃ containing octavalent osmium was prepared and characterized. The results of the investigations indicate that OsO₂F₄ and higher fluorides of osmium than OsF₆ are unlikely to be stable at ordinary temperatures and pressures. The oxidizing properties of the noble metal hexa-fluorides have been investigated. The reactions of platinum hexafluoride with nitrogen trifluoride, carbon monoxide, krypton, chlorine and hexafluorobenzene have been studied with the aim of preparing some unusual cations and to set an upper limit to the oxidizing power of PtF₆. The reaction of xenon with platinum hexafluoride was further investigated in order to better characterize the reaction product. Dioxygenyl hexa-fluoroplatinate (V) was prepared on a large scale for a neutron diffraction study. This study was carried out by J.A Ibers and W.C. Hamilton of the Brookhaven National Laboratory. Interpretation of their findings is given. Reactions of nitric oxide with OsF₆ , IrF₆ and PtF₆ were investigated to establish the oxidizing trend in the series and to prepare as complete a series of NOMF₆ salts as possible. The products NOMF₆ were characterized by analysis, magnetic measurements and X-ray powder photography. Reactions of these hexa-fluorides with sulphur tetrafluoride were also investigated and products containing SF₃⁺ cations were obtained and characterized.

Text

2011-10-28

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http://hdl.handle.net/2429/38402

Chemistry

University of British Columbia

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