Xenon hexafluoride

Xenon hexafluoride is a noble gas compound with the formula XeF₆ and the highest of the three binary fluorides of xenon, the other two being XeF₂ and XeF₄. All are exergonic and stable at normal temperatures. XeF₆ is the strongest fluorinating agent of the series. At room temperature, it is a colorless solid that readily sublimes into intensely yellow vapors.

Preparation

Xenon hexafluoride can be prepared by long-term heating of XeF₂ at about 300°C and pressure 6 MPa (60 atmospheres).

With as catalyst, however, this reaction can proceed at 120°C even in xenon-fluorine molar ratios as low as 1:5.

Structure

The structure of XeF₆ required several years to establish in contrast to the cases of and . In the gas phase the compound is monomeric. VSEPR theory predicts that due to the presence of six fluoride ligands and one lone pair of electrons the structure lacks perfect octahedral symmetry, and indeed electron diffraction combined with high-level calculations indicate that the compound's point group is C_3v. The calculated energy for the point group O_h is only insignificantly higher, indicating that the minimum on the energy surface is very shallow. Konrad Seppelt, an authority on noble gas and fluorine chemistry, says, "the structure is...
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