Xenon tetroxide

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Xenon tetroxide
Xenon tetroxide
Xenon tetroxide
Space-filling model of the xenon tetroxide molecule
Space-filling model of the xenon tetroxide molecule
Names
IUPAC names
Xenon tetraoxide
Xenon(VIII) oxide
Other names
Xenon tetroxide
Perxenic anhydride
Identifiers
3D model (
JSmol
)
ChemSpider
  • InChI=1S/O4Xe/c1-5(2,3)4 checkY
    Key: VHWKDFQUJRCZDZ-UHFFFAOYSA-N checkY
  • InChI=1/O4Xe/c1-5(2,3)4
    Key: VHWKDFQUJRCZDZ-UHFFFAOYAS
SMILES
  • O=[Xe](=O)(=O)=O
Properties
XeO4
Molar mass 195.29 g mol−1
Appearance Yellow solid below −36 °C
Melting point −35.9 °C (−32.6 °F; 237.2 K)
Boiling point 0 °C (32 °F; 273 K)[1]
reacts
Structure
Tetrahedral[2]
0 D
Thermochemistry
Std enthalpy of
formation
(ΔfH⦵298)
 +153.5 kcal mol−1 [3]
Hazards
Occupational safety and health (OHS/OSH):
Main hazards
 powerful explosive
Related compounds
Related compounds
Perxenic acid
Xenon trioxide
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Xenon tetroxide is a

compound of a noble gas. It is a yellow crystalline solid that is stable below −35.9 °C; above that temperature it is very prone to exploding and decomposing into elemental xenon and oxygen (O2).[4][5]

All eight valence electrons of xenon are involved in the bonds with the oxygen, and the oxidation state of the xenon atom is +8. Oxygen is the only element that can bring xenon up to its highest oxidation state; even fluorine can only give XeF6 (+6).

Two other short-lived xenon compounds with an oxidation state of +8, XeO3F2 and XeO2F4, are accessible by the reaction of xenon tetroxide with xenon hexafluoride. XeO3F2 and XeO2F4 can be detected with mass spectrometry. 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 ΔH = −643 kJ/mol:

XeO4 → Xe + 2 O2

Xenon tetroxide dissolves in water to form perxenic acid and in alkalis to form perxenate salts:

XeO4 + 2 H2O → H4XeO6
XeO4 + 4 NaOH → Na4XeO6 + 2 H2O

Xenon tetroxide can also react with xenon hexafluoride 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 of xenates to perxenates and xenon:

2 HXeO−
4 + 2 OH− → XeO4−
6 + Xe + O2 + 2 H2O

The other is oxidation of the xenates with ozone in basic solution:

HXeO−
4 + O3 + 3 OH− → XeO4−
6 + O2 + 2 H2O

Barium perxenate is reacted with sulfuric acid and the unstable perxenic acid is dehydrated to give xenon tetroxide:[6]

Ba
2XeO
6 + 2 H
2SO
4 → 2 BaSO
4 + H
4XeO
6
H
4XeO
6 → 2 H
2O + XeO
4

Any excess perxenic acid slowly undergoes a decomposition reaction to xenic acid and oxygen:

2 H
4XeO
6 → O
2 + 2 H
2XeO
4 + 2 H
2O

References

  1. ^ Lide, David R. (1998). Handbook of Chemistry and Physics (87 ed.). Boca Raton, Florida: CRC Press. p. 494.
    ISBN 0-8493-0594-2
    .
  2. doi:10.1063/1.1673060
    .
  3. doi:10.1021/ja01088a038
    .
  4. ^ H.Selig, J. G. Malm, H. H. Claassen, C. L. Chernick, J. L. Huston (1964). "Xenon tetroxide – Preparation & Some Properties". Science. 143 (3612): 1322–3.
    S2CID 29205117.{{cite journal}}: CS1 maint: multiple names: authors list (link
    )
  5. ^ J. L. Huston; M. H. Studier; E. N. Sloth (1964). "Xenon tetroxide — Mass Spectrum". Science. 143 (3611): 1162–3.
    S2CID 28547895
    .
  6. ISBN 9780080501093
    .
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