Carbon oxohalides are a group of chemical compounds that contain only carbon, oxygen and halogen atoms: fluorine, chlorine, bromine and iodine.
The halogen atoms X do not have to be identical; they differ in mixed oxohalides.
Most combinations of halogens exist but carbonyl iodide, COI2, is unknown.
The carbon–oxygen bond length in carbonyl halides (1.13–1.17 Å)[1] is shorter than in other carbonyl compounds[2] such as aldehydes and ketones, carboxylic acids, esters and amides (1.20–1.21 Å).
[3] They are reactive reagents for halogenation,[1] acylation and dehydration reactions.