Chemistry:Dichlorine hexoxide

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Dichlorine hexoxide
Space-filling model of the dichlorine hexoxide molecule
Space-filling model of the dichlorine hexoxide molecule
Space-filling model of the component ions of dichlorine hexoxide
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
Properties
Cl
2
O
6
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
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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Infobox references
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Dichlorine hexoxide is the chemical compound with the molecular formula Cl
2
O
6
or O
2
Cl–O–ClO
3
, 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 [ClO
2
]+
[ClO
4
]
, which may be thought of as the mixed anhydride of chloric and perchloric acids. This compound is a notable perchlorating agent.[1]

Molecular structure

It was originally reported to exist as the monomeric chlorine trioxide ClO
3
in gas phase,[2] but was later shown to remain an oxygen-bridged dimer after evaporation and until thermal decomposition into chlorine perchlorate, Cl
2
O
4
, and oxygen.[3] The compound ClO
3
was then rediscovered.[4]

It is a dark red fuming liquid at room temperature that crystallizes as a red ionic compound, chloryl perchlorate, [ClO
2
]+
[ClO
4
]
. 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).

Properties

Cl
2
O
6
is diamagnetic and is a very strong oxidizing agent. Although stable at room temperature, it explodes violently on contact with organic compounds[5] It is a strong dehydrating agent:

Cl
2
O
6
+ H
2
O → HClO
4
+ HClO
3

Many reactions involving Cl
2
O
6
reflect its ionic structure, [ClO
2
]+
[ClO
4
]
, including the following:[6]

NO
2
F + Cl
2
O
6
[NO
2
]+
ClO
4
+ ClO
2
F
NO + Cl
2
O
6
[NO]+
ClO
4
+ ClO
2
2 V
2
O
5
+ 12 Cl
2
O
6
→ 4 VO(ClO
4
)
3
+ 12 ClO
2
+ 3 O
2
SnCl
4
+ 6 Cl
2
O
6
→ [ClO
2
]
2
[Sn(ClO
4
)
6
] + 4 ClO
2
+ 2 Cl
2

It reacts with gold to produce the chloryl salt [ClO
2
]+
[Au(ClO
4
)
4
]
:[7]

2 Au + 6 Cl
2
O
6
→ 2 [ClO
2
]+
[Au(ClO
4
)
4
]
+ Cl
2

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

Nevertheless, it can also react as a source of the ClO
3
radical:[citation needed]

2 AsF
5
+ Cl
2
O
6
→ 2 ClO
3
AsF
5

Synthesis

4 ClO
2
+ 2 O
3
→ 2 Cl
2
O
6
+ O
2
(under ultraviolet light)

References

  1. Jean-Louis Pascal; Frédéric Favier (1998). "Inorganic perchlorato complexes" (in en). 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. doi:10.1038/132514b0. Bibcode1933Natur.132..514G. 
  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. https://archive.org/details/conciseencyclope00eagl. 
  6. Harry Julius Emeléus, Alan George Sharpe (1963). Advances in Inorganic Chemistry and Radiochemistry. Academic Press. p. 65. ISBN 0-12-023605-2. https://books.google.com/books?id=pRXIwIV-hB8C. 
  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.