Dichlorine hexoxide

Dichlorine hexoxide
Space-filling model of the dichlorine hexoxide molecule
Space-filling model of the component ions of dichlorine hexoxide
Names
IUPAC name
Dichlorine hexoxide
Other names
Chlorine trioxide; Chloryl perchlorate; Chlorine(V,VII) oxide
Identifiers
3D model (JSmol)
ChemSpider
  • InChI=1S/Cl2O6/c3-1(4)8-2(5,6)7
    Key: BMVIIZAOKBSWDS-UHFFFAOYSA-N
  • O=[Cl](=O)O[Cl](=O)(=O)=O
  • O=[Cl+]=O.[O-]Cl(=O)(=O)=O
Properties
Cl2O6
Molar mass 166.901 g/mol
Appearance red liquid
Density 1.65 g/cm3
Melting point 3.5 °C (38.3 °F; 276.6 K)
Boiling point 200 °C (392 °F; 473 K)
Reacts
Hazards
Occupational safety and health (OHS/OSH):
Main hazards
 oxidizer
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Dichlorine hexoxide is the chemical compound with the molecular formula Cl2O6 or O2Cl−O−ClO3, which is correct for its gaseous state. However, in liquid or solid form, this chlorine oxide ionizes into the dark red ionic compound chloryl perchlorate or dioxochloronium(V) perchlorate [ClO2]+[ClO4]−, which may be thought of as the mixed anhydride of chloric and perchloric acids. This compound is a notable perchlorating agent.

Molecular structure

It was originally reported to exist as the monomeric chlorine trioxide ClO3 in gas phase, but was later shown to remain an oxygen-bridged dimer after evaporation and until thermal decomposition into chlorine perchlorate, Cl2O4, and oxygen. The compound ClO3 was then rediscovered.

It is a dark red fuming liquid at room temperature that crystallizes as a red ionic compound, chloryl perchlorate, [ClO2]+[ClO4]−. The red color shows the presence of chloryl ions. Thus, chlorine's formal oxidation state in this compound remains a mixture of chlorine(V) and chlorine(VII) both in the gas phase and when condensed; however by breaking one oxygen-chlorine bond some electron density does shifts towards the chlorine(VII).[citation needed]

Properties

Cl2O6 is diamagnetic and is a very strong oxidizing agent. Although stable at room temperature, it explodes violently on contact with organic compounds It is a strong dehydrating agent:

Cl2O6 + H2O → HClO4 + HClO3

Many reactions involving Cl2O6 reflect its ionic structure, [ClO2]+[ClO4]−, including the following:

NO2F + Cl2O6 → [NO2]+ClO−4 + ClO2F
NO + Cl2O6 → [NO]+ClO−4 + ClO2
2 V2O5 + 12 Cl2O6 → 4 VO(ClO4)3 + 12 ClO2 + 3 O2
SnCl4 + 6 Cl2O6 → [ClO2]2[Sn(ClO4)6] + 4 ClO2 + 2 Cl2

It reacts with gold to produce the chloryl salt [ClO2]+[Au(ClO4)4]−:

2 Au + 6 Cl2O6 → 2 [ClO2]+[Au(ClO4)4]− + Cl2

Several other transition metal perchlorate complexes are prepared using dichlorine hexoxide.

Nevertheless, it can also react as a source of the ClO3 radical:[citation needed]

2 AsF5 + Cl2O6 → 2 ClO3AsF5

Synthesis

4 ClO2 + 2 O3 → 2 Cl2O6 + O2 (under ultraviolet light)

References

  1. ↑ Jean-Louis Pascal; Frédéric Favier (1998). "Inorganic perchlorato complexes". Coordination Chemistry Reviews. 178–180 (1): 865–902. doi:10.1016/S0010-8545(98)00102-7.
  2. ↑ C. F. Goodeve, F. A. Todd (1933). "Chlorine Hexoxide and Chlorine Trioxide". Nature. 132 (3335): 514–515. Bibcode:1933Natur.132..514G. doi:10.1038/132514b0. S2CID 4116929.
  3. ↑ Lopez, Maria; Juan E. Sicre (1990). "Physicochemical properties of chlorine oxides. 1. Composition, ultraviolet spectrum, and kinetics of the thermolysis of gaseous dichlorine hexoxide". J. Phys. Chem. 94 (9): 3860–3863. doi:10.1021/j100372a094.
  4. ↑ Grothe, Hinrich; Willner, Helge (1994). "Chlorine Trioxide: Spectroscopic Properties, Molecular Structure, and Photochemical Behavior". Angew. Chem. Int. Ed. 33 (14): 1482–1484. doi:10.1002/anie.199414821.
  5. ↑ Mary Eagleson (1994). Concise encyclopedia chemistry. Walter de Gruyter. p. 215. ISBN 3-11-011451-8.
  6. ↑ Harry Julius Emeléus, Alan George Sharpe (1963). Advances in Inorganic Chemistry and Radiochemistry. Academic Press. p. 65. ISBN 0-12-023605-2. {{cite book}}: ISBN / Date incompatibility (help)
  7. ↑ Cunin, Frédérique; Catherine Deudon; Frédéric Favier; Bernard Mula; Jean Louis Pascal (2002). "First Anhydrous Gold Perchlorato Complex: ClO2Au(ClO4)4. Synthesis and Molecular and Crystal Structure Analysis". Inorganic Chemistry. 41 (16): 4173–4178. doi:10.1021/ic020161z. PMID 12160405.