Some preparations and properties of high oxidation state transition-metal fluorides and chalcogenide fluorides.

The work presented in this thesis is divided into two parts. In the first the preparation, characterisation, physical properties and chemistry of the noble was fluoride MrF2 are reviewed. In the present work the oxidizing power of MrF2 is investigated in its reaction with transition metals chromium and osmium and in its reaction with MoF3 at room temperature in HF. CrF5 and CsP5 are the highest oxidation state metal fluorides produced. The compounds were identified by infrared and 19F NMR spectroscopy and, in the case of CrF5, mass spectrometry. EJR spectroscopy has revealed the structure of CrF5 in solution. At -60C CrF5 is present as a fluorine bridged pentamer. The reaction of KrF2 with MnF3 appears to result in oxidation but no clear evidence has been obtained for anything other than starting material. In the second part of the thesis present advances in the preparation of transition metal chalcogenide fluorides are reviewed. The present work investigates the reaction of WF6 with Sb2Te3, MoF6 with Sb2X3 (X = S, Se, Te), MF5 (M = Ta, Nb) with Sb2S3, TaF5 with Sb2Se3, ReF6 with Sb2X3 (X = S, Se) and UF6 with Sb2S3. New compounds MoSF4, MoSeF4, ReSF4 and ReSeF4 have been prepared and characterized. All these compounds appear to exist as fluorine bridged polymers are highly sensitive to air and moisture decomposing to give HF and H2S or H2Se. No clear results were obtained to enable new compounds prepared by reaction of MF5 (M = Ta, Nb) with Sb2S3 results in the reduction of the hexafluoride to a mixture of UF5 and UF4 or to U2F9 depending on the reaction conditions.