Chlorine tetroxide
{{Chembox
| Name = Chlorine tetroxide
|ImageFile=ClO4.svg
| IUPACName = Tetraoxidochlorine
| Section1 = {{Chembox Identifiers
| CASNo = 12133-63-0
| CASNo_Ref = {{Cascite|changed|??}}{{cite web |title=Perchloryloxy|work=Active Thermochemical Tables |url=https://atct.anl.gov/Thermochemical%20Data/version%201.148/species/?species_number=1158}}
| ChEBI = 29420
| ChemSpiderID = 4574089
| PubChem = 5460591
| SMILES = O=Cl(=O)(=O)[O]
| InChI = 1S/ClO4/c2-1(3,4)5
| InChIKey = UXZQWBXGIHHEHG-UHFFFAOYSA-N
| Gmelin = 239881}}
| Section2 = {{Chembox Properties
| Formula = ClO4
| MolarMass = 99.45 g mol−1}}
}}
Chlorine tetroxide is an unstable chlorine oxide with the chemical formula {{chem2|ClO4}}.
History
=Gomberg's mistaken 1923 production=
In 1923, chemist Moses Gomberg proposed a production method of chlorine tetroxide. He claimed that treating iodine and silver perchlorate in anhydrous diethyl ether produced it.{{cite journal|last=Gomberg|first=M.|journal=Journal of the American Chemical Society|date=1 February 1923|volume=45|issue=2|pages=398–421|doi=10.1021/ja01655a017|title=The Reaction Between Silver Perchlorate and Iodine. Chlorine Tetra-Oxide}}
:I2 + 2 AgClO4 → 2 AgI + (ClO4)2
However, later researchers claimed that the product was iodine perchlorate.{{cite journal|last=Alcock|first=N. W.|author2=Waddington, T. C.|title=478. The reaction between iodine and silver perchlorate|journal=Journal of the Chemical Society (Resumed)|date=1 January 1962|pages=2510|doi=10.1039/JR9620002510}} So far, however, there is no certain evidence for the existence of iodine perchlorate either.
Properties
The electron affinity energy of chlorine tetroxide can be figured out using the Born–Haber cycle and the lattice energy data of perchlorates. It is about 561 kJ/mol.{{in lang|zh-hans}}{{cite book|title=《无机化学丛书》第六卷：卤素、铜分族、锌分族|page=272|author=张青莲|date=1991 |isbn=7-03-002238-6|location=北京|publisher=科学出版社}}
The structure of chlorine tetroxide is uncertain; the molecular point group may be Cs, C2v, or Td.{{cite journal|last=Kopitzky|first=Rodion |author2=Grothe, Hinrich |author3=Willner, Helge|title=Chlorine Oxide Radicals ClOx (x=1–4) Studied by Matrix Isolation Spectroscopy|journal=Chemistry: A European Journal|date=16 December 2002|volume=8|issue=24|pages=5601–5621|doi=10.1002/1521-3765(20021216)8:24<5601::AID-CHEM5601>3.0.CO;2-Z|pmid=12693042 }}
In a solid oxygen matrix ClO4 reacts to form ClO6Cl, which has three double bonded oxygen atoms, and a chain of three oxygen atoms -O-O-O• attached to the chlorine.