Xenon trioxide (XeO₃) is extremely explosive as well as shock-, temperature-, and light-sensitive. It can be synthesized by the hydrolysis of XeF₄ and crystallized by slow evaporation of its aqueous solution. XeO₃ obtained in this way has been characterized using X-ray crystallography and was found to form an orthorhombic phase (α-XeO₃) with the space group P2₁2₁2₁.

James T. Goettel and Gary J. Schrobilgen, McMaster University, Hamilton, Ontario, Canada, have reinvestigated the solid-state structure of the compound and found two new phases by modifying the crystallization conditions. The team obtained α-XeO₃ by slowly evaporating a solution of XeO₃ in 48 % HF solution. β-XeO₃ was synthesized by slow water evaporation from aqueous XeO₃ solutions. Evaporation of a solution of XeO₃ in propionitrile (H₃CCH₂CN) gave crystals of γ-XeO₃.

The researchers characterized the obtained phases by single-crystal X-ray crystallography and Raman spectroscopy. They obtained a more precise structure of α-XeO₃ that was in agreement with previously reported data. The β– and γ-phases are rhombohedral with the point groups R3 and R3c, respectively. According to the team, all three structures feature Xe=O—Xe bridges resulting from the simultaneous donor and acceptor properties of XeO₃.

• Solid-State Structures of XeO₃,
  James T. Goettel, Gary J. Schrobilgen,
  Inorg. Chem. 2016.
  DOI: 10.1021/acs.inorgchem.6b02371