Syntheses and vibrational spectra of xenon(VI) fluorozirconate(IV) and xenon(VI) fluorohafnate(IV)

Abstract Liquid xenon difluoride at 140°C does not react with zirconium or hafnium tetrafluorides, neither does liquid xenon hexafluoride at 60°C. Therefore reactions between the corresponding hydrazinium fluorometalates or ammonium fluorometalates and xenon difluoride and xenon hexafluoride, respectively, were carried out. N 2 H 6 ZrF 6 and N 2 H 6 HfF 6 react with xenon difluoride at 60°C again yielding only the corresponding tetrafluorides, while the analogous reaction with (NH 4 ) 2 ZrF 6 and (NH 4 ) 2 HfF 6 proceeds at 170°C yielding the corresponding ammonium pentafluorometalates, which are stable and do not react further with excessive xenon difluoride up to 200°C. The reaction between N 2 H 6 ZrF 6 or N 2 H 6 HfF 6 and xenon hexafluoride proceeds at room temperature yielding a series of thermally unstable compounds of the type mXeF 6 .MF 4 (M = Zr, Hf) where m ⩽ 6. The final products which are stable at room temperature are XeF 6 .MF 4 (M = Zr,Hf). Spectroscopic evidence suggests that these compounds are salts of a XeF + 5 cation squashed between a polymeric anion of the type (MF 5 ) x- x .