Spectroscopic studies and some reaction chemistry of transition-metal oxide fluorides.

Chapter 1 of the thesis gives a introduction to the area of study and outlines previous literature reports together with the reasons for our choice of organic reagents. Chapter 2 gives the reader a review of the reported properties, spectroscopy and reactions of some transition-metal oxide fluorides. Chapters 3-5 summarise an examination of the reactivity of the oxide fluorides VOF3, CrO2F4, CrOF4, M0OF4, WOF4, ReO3F, ReO2F3, ReOF4, ReOF5, OSOF4, OsOF5, OsO2F3 and OSO3F2 at ambient temperature with a range of simple halocarbons (CCl4, CFCl3) and hydrohalocarbons (CH2Cl2, CHCl3, CH2Br2, CF3CH2Cl). The reactivity of UF6 and XeF2 with similar organic compounds is examined in Chapters 6 and 7. Cr02F2, CrOF4, ReO3F and ReO2F3 were found to be inert towards the organic substrates employed and VOF3 was found to undergo only a trace reaction. The remaining oxide fluorides were found to undergo remarkably selective reaction to yield primarily chlorine- fluorine or bromine-fluorine exchange products. The reactivity and selectivity were then explained in terms of structure, solubility and oxidation state. UF6 was found to undergo very selective hydrogen-fluorine exchange with CH2Cl2 and CF3CH2Cl and gave predominantly hydrogen-fluorine exchange with CHCl3. Reaction with CH2Br2, CCl4 and CFCl3 yielded halogen exchange. XeF2 was found to react with CH2Cl2 and CHCl3 with low selectivity and to be inert towards CF3CH2Cl. Slow reactions were observed with CCl4, CFCl3 and CF2ClCFCl2. Such reactions are believed to be catalysed by HF. Attempted ESR studies on the d1 osmium (VII) oxide fluorides OsOF5 and OsO2F3 are reported. The spectrum obtained for OsOF5 was fully assigned, this being the first assigimient of an Os(VII) ESR (see Chapter 8). The rhenium oxide fluorides were isolated as monomers in inert matrices and their infrared and UV-visible spectra were recorded and assigned (see Chapter 9).