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Complexes of inorganic pentafluorides.

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posted on 19.11.2015, 08:48 by Ian Leonard. Wilson
The reactions of the group V pentafluorides with the oxides of nitrogen have been studied. Phosphorus pentafluoride does not react at room temperature with nitric oxide, and the only involatile product formed in the reaction of arsenic pentafluoride with nitric oxide is NOAsF6. The other reactions yield complex mixtures of involatile solids, all of which contain nitrosoniurn and/or nitronium salts. Evidence is presented for the formation in these reactions of complex oxyfluoride species containing anions of general formula (MOF4)- (M = P, As, Sb). The products formed in the reactions of antimony pentafluoride are more complex than those formed in the corresponding reactions of phosphorus and arsenic pentafluorides. The Sb2F11- anion is frequently formed, and in systems where the oxide of nitrogen reacts in the liquid phase, nitrito-or nitrato-fluorides can be isolated. Phosphorus trifluoride forms a stable l:l complex with antimony pentafluoride and an unstable complex with arsenic pentafluoride. Spectroscopic evidence suggests that these are ionic or fluorine- bridged species. The existence of a weak complex between antimony pentafluoride and carbon monoxide is also indicated. Ruthenium pentafluoride is reduced by carbon monoxide at 200°C to a moisture-sensitive solid of composition Ru(CO)F3.5. Spectroscopic, magnetic and chemical evidence are consistent with a formulation of this compound as [Ru(CO)2F+.RuF6-]n. This compound can react further with carbon monoxide to give a series of moisture- sensitive carbonyl fluorides, but under extreme conditions of temperature and pressure, the air-stable species Ru(CO)2F2 is formed. Carbonyl fluorides of osmium and iridium can also be formed by reaction of higher fluorides with carbon monoxide. The reactions of phosphorus trifluoride and carbon monoxide with PtF4.2BrF3, and with platinum tetrafluoride obtained by the thermal decomposition of this complex, have been investigated. The isolation of Pt(PF3)2Br2 and Pt(CO)2Br2 from these reactions, and the existence of the previously reported carbonyl fluoride, Pt(CO)2F8, are discussed.


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University of Leicester

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