Interhalogen

An interhalogen compound is a chemical compound where there is a chemical bond between two different halogen atoms. Normally, these are fluorine, chlorine, bromine, and iodine. Compounds between astatine and the stable halogens have been made, but astatine is too radioactive to study their chemistry before it decays. No compounds of tennessine have been made.

Normally interhalogens are quite toxic and reactive. Some examples would be chlorine trifluoride or bromine monochloride. The common molecular formula of a binary interhalogen is CX_n: one central halogen atom C surrounded by n atoms of a different, lighter halogen X. n can be either 1, 3, 5, or 7, depending on the oxidation state of the central atom.

Because the interhalogen bond is so weak, it is not commonly found in other compounds. The main other class of compounds with these bonds are the oxyhalides of halogens, such as perchloryl fluoride; these compounds are more stable than true interhalogens.

Organic compounds with interhalogen bonds are rare. Iodobenzene dichloride and related iodanes with the iododichloride functional group have a similar T-shaped molecular geometry to iodine trichloride, with a straight line of Cl−I−Cl bonds and the organic part attached nearly perpendicular at the iodine atom.

Uses

Interhalogens are strong oxidizers. They are also used to add halogen atoms to other molecules (halogenation).