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