Editing Interhalogen (section)

{{Short description|Molecule containing only halogen elements of two or more kinds}}

In [[chemistry]], an '''interhalogen compound''' is a [[molecule]] which contains two or more different [[halogen]] atoms ([[fluorine]], [[chlorine]], [[bromine]], [[iodine]], or [[astatine]]) and no atoms of elements from any other group. 

Most interhalogen compounds known are binary (composed of only two distinct elements). Their formulae are generally {{chem2|XY_{''n''} }}, where ''n'' = 1, 3, 5 or 7, and X is the less [[electronegativity|electronegative]] of the two halogens. The value of ''n'' in interhalogens is always odd, because of the odd valence of halogens. They are all prone to [[hydrolysis]], and ionize to give rise to polyhalogen ions. Those formed with astatine have a very short half-life due to astatine being intensely radioactive.

No interhalogen compounds containing three or more different halogens are definitely known,<ref name = "Chemistry of Interhalogens"/> although a few books claim that {{chem2|IFCl2}} and {{chem2|IF2Cl}} have been obtained,<ref>{{Greenwood&Earnshaw2nd|page=824}}</ref><ref name=Meyers/><ref name=Murthy/><ref name=Sahoo/> and theoretical studies seem to indicate that some compounds in the series {{chem|BrClF|''n''}} are barely stable.<ref name=Ignatiev/>

Some interhalogens, such as {{chem2|BrF3}}, {{chem2|IF5}}, and {{chem2|ICl}}, are good [[halogenation|halogenating]] agents. {{chem2|BrF5}} is too reactive to generate fluorine. Beyond that, [[iodine monochloride]] has several applications, including helping to measure the saturation of fats and oils, and as a [[catalyst]] for some [[chemical reaction|reactions]]. A number of interhalogens, including [[Iodine heptafluoride|{{chem2|IF7}}]], are used to form [[polyhalide]]s.<ref name = "Chemistry of Interhalogens"/>

Similar compounds exist with various [[pseudohalogen]]s, such as the halogen [[azide]]s ({{chem2|[[fluorine azide|FN3]]}}, {{chem2|[[chlorine azide|ClN3]]}}, {{chem2|[[bromine azide|BrN3]]}}, and {{chem2|[[iodine azide|IN3]]}}) and [[cyanogen]] halides ({{chem2|[[cyanogen fluoride|FCN]]}}, {{chem2|[[cyanogen chloride|ClCN]]}}, {{chem2|[[cyanogen bromide|BrCN]]}}, and {{chem2|[[cyanogen iodide|ICN]]}}).