Interhalogen and polyhalogen compounds

Binary compounds identified as interhalogen compounds with stoichiometry XY_n are found among every pair of halogens F-I. N is an odd number for neutral molecules and when n>1 the terminal atom Y is all the time the lighter element. The greatest n found with a given pair increases with the variation in period number, some instances being IBr, BrF_5, ICl₃, and IF₇. Most interhalogen compounds are obtained by direct reaction. They are very strongly oxidizing and the fluorides are fine fluorinating agents.

Several interhalogen and cations and polyhalogen anions are also known, some forming simply. For instance, aqueous solutions consisting of I^- dissolve I₂ to create I^-₃. In liquid BrF3 the following equilibrium take place:

With the solvent-system concept In accordance, fluoride donors like NaF act as bases in this medium (providing Na⁺ and BrF₄^-), and fluoride acceptors like SbF₅ act as acids (providing BrF₂⁺and SbF₆^- ).

Another cationic species can be prepared through strong oxidation of the elements (example with AsF5) in a appropriate nonaqueous solvent. Instances include CI₃⁺and Br₂⁺ and I₅⁺ that are also known in solid salts with anions like AsF₆^- .

Several species have the structures predicted through the VSEPR model. Listed as per the steric number (SN) below, the geometries and point groups are