Dichlorine trioxide[1]
IUPAC name
dichlorine trioxide
Other names
chlorine trioxide
chlorine chlorate
chlorine(I,V) oxide
3D model (JSmol)
  • InChI=1S/Cl2O3/c1-5-2(3)4 checkY
  • InChI=1/Cl2O3/c1-5-2(3)4
  • ClOCl(=O)=O
Molar mass 118.903 g/mol
Appearance dark brown solid
Melting point explodes below 0 °C
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
☒N verify (what is checkY☒N ?)

Dichlorine trioxide, Cl2O3, is a chlorine oxide. It is a dark brown solid discovered in 1967 which is explosive even below 0 °C.[2] It is formed by the low-temperature photolysis of ClO2 and is formed along with Cl2O6, Cl2 and O2. Its structure is believed to be OCl−ClO2 with possible isomers such as Cl−O−ClO2.[3] The isomer having a structure of OCl–O–ClO would be the theoretical anhydride of chlorous acid.


  1. ^ Lide, David R. (1998). Handbook of Chemistry and Physics (87 ed.). Boca Raton, Florida: CRC Press. pp. 4–51. ISBN 0-8493-0594-2.
  2. ^ N. N. Greenwood and A. Earnshaw (1997). Chemistry of the Elements. Butterworth-Heinemann. ISBN 978-0750633659.
  3. ^ Egon Wiberg, Arnold Frederick Holleman (2001) Inorganic Chemistry, Elsevier ISBN 0-12-352651-5