Xenon difluoride as a fluoride ion donor. Evidence for the salts [Xe2F3]+[MF6]–,[XeF]+[MF6]– and [XeF]+[M2F11]–

Abstract

Xenon difluoride has been shown to be a fluoride ion donor. With bromine pentafluoride as solvent, a series of compounds of general formula 2XeF₂,MF₅(M = As, Ru, Os, Ir, Pt), XeF₂,MF₅(M = As, Ru, Os, Ir, Pt), and XeF₂,2MF₅(M = Ru, Ir, Pt) have been prepared. The noble-metal compounds in each series are isomorphous. Raman and i.r. spectroscopy have established that the noble-metal compounds, 2XeF₂,MF₅ contain the same cation as the fluoroarsenate, [Xe₂F₃]⁺[AsF₆]^–, the ionic formulation of which has been established by X-ray single-crystal analysis. The Raman spectra of the 1 : 1 compounds are similar to those of related, established salts, A⁺[MF₆]^–. Departures from the ideal salt spectra suggest that the [MF₆]^– symmetry is lowered by fluorine bonding of the anion with the cation: F–Xe⁺⋯ F–PtF₅^–.

The Xe₂F₃⁺ salts are characterized by strong bands in the Raman at ca. 575 and 591 cm.^–1(stretch region) and ca. 160 cm.^–1(bend region). Raman spectra of the XeF⁺ salts show an intense doublet in the region 600–612 cm.^–1(typically 601, 608 cm.^–1). The doublet nature of the band is attributed to weak interactions between cations. All the salts are thermally stable at ordinary temperatures except [XeF]⁺[OsF₆]^– which decomposes spontaneously at ca. 20° : 3 XeFOsF₆→ Xe₂F₃OsF₆+ Xe + 2 OsF₆.