Xenon tetroxide is a

chemical compound A chemical compound is a chemical substance composed of many identical molecules (or molecular entities) containing atoms from more than one chemical element held together by chemical bonds. A molecule consisting of atoms of only one element ...

xenon Xenon is a chemical element with the symbol Xe and atomic number 54. It is a dense, colorless, odorless noble gas found in Earth's atmosphere in trace amounts. Although generally unreactive, it can undergo a few chemical reactions such as the ...

and

oxygen Oxygen is the chemical element with the symbol O and atomic number 8. It is a member of the chalcogen group in the periodic table, a highly reactive nonmetal, and an oxidizing agent that readily forms oxides with most elements ...

with molecular formula XeO₄, remarkable for being a relatively stable compound of a noble gas. It is a yellow

crystal A crystal or crystalline solid is a solid material whose constituents (such as atoms, molecules, or ions) are arranged in a highly ordered microscopic structure, forming a crystal lattice that extends in all directions. In addition, macro ...

line

solid Solid is one of the four fundamental states of matter (the others being liquid, gas, and plasma). The molecules in a solid are closely packed together and contain the least amount of kinetic energy. A solid is characterized by structur ...

that is stable below −35.9 ° C; above that temperature it is very prone to exploding and decomposing into elemental xenon and oxygen (O₂). All eight

valence electron In chemistry and physics, a valence electron is an electron in the outer shell associated with an atom, and that can participate in the formation of a chemical bond if the outer shell is not closed. In a single covalent bond, a shared pair form ...

s of xenon are involved in the bonds with the oxygen, and the

oxidation state In chemistry, the oxidation state, or oxidation number, is the hypothetical charge of an atom if all of its bonds to different atoms were fully ionic. It describes the degree of oxidation (loss of electrons) of an atom in a chemical compound. C ...

of the xenon atom is +8. Oxygen is the only element that can bring xenon up to its highest oxidation state; even

fluorine Fluorine is a chemical element with the symbol F and atomic number 9. It is the lightest halogen and exists at standard conditions as a highly toxic, pale yellow diatomic gas. As the most electronegative reactive element, it is extremely reactiv ...

can only give XeF₆ (+6). Two other short-lived

xenon compounds Xenon is a chemical element with the symbol Xe and atomic number 54. It is a dense, colorless, odorless noble gas found in Earth's atmosphere in trace amounts. Although generally unreactive, it can undergo a few chemical reactions such as the f ...

with an oxidation state of +8, XeO₃F₂ and XeO₂F₄, are accessible by the reaction of xenon tetroxide with

xenon hexafluoride Xenon hexafluoride is a noble gas compound with the formula XeF6. It is one of the three binary fluorides of xenon, the other two being XeF2 and XeF4. All known are exergonic and stable at normal temperatures. XeF6 is the strongest fluorinati ...

. XeO₃F₂ and XeO₂F₄ can be detected with

mass spectrometry Mass spectrometry (MS) is an analytical technique that is used to measure the mass-to-charge ratio of ions. The results are presented as a '' mass spectrum'', a plot of intensity as a function of the mass-to-charge ratio. Mass spectrometry is u ...

. The perxenates are also compounds where xenon has the +8 oxidation state.

Reactions

At temperatures above −35.9 °C, xenon tetroxide is very prone to explosion, decomposing into xenon and oxygen gases with Δ''H'' = −643 kJ/mol: :XeO₄ → Xe + 2 O₂ Xenon tetroxide dissolves in water to form

perxenic acid In chemistry, perxenates are salts of the yellow xenon-containing anion . This anion has octahedral molecular geometry, as determined by Raman spectroscopy, having O–Xe–O bond angles varying between 87° and 93°. The Xe–O bond length was ...

and in alkalis to form perxenate salts: :XeO₄ + 2 H₂O → H₄XeO₆ :XeO₄ + 4 NaOH → Na₄XeO₆ + 2 H₂O Xenon tetroxide can also react with

to give xenon oxyfluorides: :XeO₄ + XeF₆ → XeOF₄ + XeO₃F₂ :XeO₄ + 2XeF₆ → XeO₂F₄ + 2 XeOF₄

Synthesis

All syntheses start from the perxenates, which are accessible from the xenates through two methods. One is the

disproportionation In chemistry, disproportionation, sometimes called dismutation, is a redox reaction in which one compound of intermediate oxidation state converts to two compounds, one of higher and one of lower oxidation states. More generally, the term can ...

of xenates to perxenates and xenon: : 2 + 2 OH⁻ → + Xe + O₂ + 2 H₂O The other is oxidation of the xenates with

ozone Ozone (), or trioxygen, is an inorganic molecule with the chemical formula . It is a pale blue gas with a distinctively pungent smell. It is an allotrope of oxygen that is much less stable than the diatomic allotrope , breaking down in the l ...

in basic solution: : + O₃ + 3 OH⁻ → + O₂ + 2 H₂O Barium perxenate is reacted with

sulfuric acid Sulfuric acid (American spelling and the preferred IUPAC name) or sulphuric acid ( Commonwealth spelling), known in antiquity as oil of vitriol, is a mineral acid composed of the elements sulfur, oxygen and hydrogen, with the molecular fo ...

and the unstable perxenic acid is dehydrated to give xenon tetroxide: : + 2 → 2 + : → 2 + Any excess

slowly undergoes a decomposition reaction to xenic acid and oxygen: : 2 → + 2 + 2

References

* {{DEFAULTSORT:Xenon Tetroxide Xenon(VIII) compounds Inorganic compounds Oxides