Topic summary
Chlorine trioxide

Extracted from the Wikipedia article Dichlorine hexoxide.
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.