Editing Interhalogen (section)

===Diatomic interhalogens===
[[File:Iodine-monochloride-3D-vdW.png|thumb|176x176px|[[Iodine monochloride]]]]
The interhalogens of form XY have physical properties intermediate between those of the two parent halogens. The [[covalent]] bond between the two atoms has some [[Ionic bond|ionic]] character, the less [[electronegative]] halogen, X, being oxidised and having a partial positive charge. All combinations of fluorine, chlorine, bromine, and iodine that have the above-mentioned general formula are known, but not all are stable. Some combinations of astatine with other halogens are not even known, and those that are known are highly unstable.

*'''[[Chlorine monofluoride]]''' (ClF) is the lightest interhalogen compound. ClF is a colorless gas with a [[normal boiling point]] of −100&nbsp;°C.
*'''[[Bromine monofluoride]]''' (BrF) has not been obtained as a pure compound — it dissociates into the trifluoride and free [[bromine]]. It is created according to the following equation:
::Br<sub>2</sub>(l) + F<sub>2</sub>(g) → 2&nbsp;BrF(g)
:Bromine monofluoride dissociates like this:
::3&nbsp;BrF → Br<sub>2</sub> + BrF<sub>3</sub>

[[File:Astatine-chloride-3D-vdW.png|thumb|177x177px|Astatine chloride]][[File:Astatine-bromide-3D-vdW.png|thumb|[[Astatine bromide]]|179x179px]][[File:Astatine-iodide-3D-vdW.svg|thumb|[[Astatine iodide]]|177x177px]]

*'''[[Iodine monofluoride]]''' (IF) is unstable and decomposes at 0&nbsp;°C, [[Disproportionation|disproportionating]] into elemental iodine and [[iodine pentafluoride]].
*'''[[Bromine monochloride]]''' (BrCl) is a yellow-brown gas with a boiling point of 5&nbsp;°C. 
*'''[[Iodine monochloride]]''' (ICl) exists as red transparent crystals that melt at 27.2&nbsp;°C to form a choking brownish liquid (similar in appearance and weight to [[bromine]]). It reacts with HCl to form the strong acid HICl<sub>2</sub>. The [[crystal structure]] of iodine monochloride consists of puckered zig-zag chains, with strong interactions between the chains. 
*'''Astatine monochloride'''<ref><sup>211</sup>At+Cl<sub>2</sub> at room temperature: {{cite book |url= https://inis.iaea.org/collection/NCLCollectionStore/_Public/12/609/12609573.pdf |page= 32 |title= Organic Chemistry of Astatine |first1= Klara |last1= Berei |first2= L. |last2= Vasáros |isbn= 9633717876 |year= 1981 |publisher= Hungarian Academy of Sciences, Central Research Institute for Physics }}</ref> (AtCl) is made either by the direct combination of gas-phase [[astatine]] with chlorine or by the sequential addition of astatine and dichromate ion to an acidic chloride solution.
*'''[[Iodine monobromide]]''' (IBr) is made by the direct combination of the elements to form a dark red crystalline solid. It melts at 42&nbsp;°C and boils at 116&nbsp;°C to form a partially dissociated vapour. 
*'''[[Astatine bromide|Astatine monobromide]]''' (AtBr) is made by the direct combination of astatine with either bromine vapour or an aqueous solution of iodine monobromide.
*'''[[Astatine iodide|Astatine monoiodide]]''' (AtI) is made by direct combination of astatine and iodine.

No astatine fluorides<!--AtF, AtF5, or whatever else, "no" means "no" (not AtF, not AtF5, not At45F387, or whatever)--> have been discovered yet. Their absence has been speculatively attributed to the extreme reactivity of such compounds, including the reaction of an initially formed fluoride with the walls of the glass container to form a non-volatile product.{{efn|An initial attempt to fluoridate astatine using [[chlorine trifluoride]] resulted in formation of a product which became stuck to the glass. Chlorine monofluoride, chlorine, and [[tetrafluorosilane]] were formed. The authors called the effect "puzzling", admitting they had expected formation of a volatile fluoride.<ref>{{cite journal |first1=E. H.|last1=Appelman|first2=E. N.|last2=Sloth|first3=M. H. |last3=Studier |year=1966 |title=Observation of astatine compounds by time-of-flight mass spectrometry |journal=Inorganic Chemistry |volume=5 |issue = 5|pages=766–769 |doi=10.1021/ic50039a016}}</ref> Ten years later, the compound was predicted to be non-volatile, out of line with the other halogens but similar to [[radon difluoride]];<ref>{{cite journal |first1=K. S.|last1=Pitzer|year=1975 |title=Fluorides of radon and element 118 |journal=Journal of the Chemical Society, Chemical Communications |volume=5 |issue = 18|pages=760b–761 |doi=10.1039/C3975000760B|url=https://escholarship.org/uc/item/8xz4g1ff}}</ref> by this time, the latter had been shown to be ionic.<ref>{{cite encyclopedia | last1 = Bartlett | first1 = N. | last2 = Sladky | first2 = F. O. | editor1-first = J. C. | editor1-last = Bailar | editor2-first= H. J. | editor2-last = Emeléus | editor3-first = R. | editor3-last = Nyholm | editor4-first = A. F. | editor4-last = Trotman-Dickenson | display-editors=3| encyclopedia =Comprehensive Inorganic Chemistry | title = The chemistry of krypton, xenon and radon | year = 1973 | publisher = Pergamon | volume = 1 | isbn = 0-08-017275-X | pages =213–330}}</ref>}} Thus, although the synthesis of an astatine fluoride is thought to be possible, it may require a liquid halogen fluoride solvent, as has already been used for the characterization of radon fluorides.{{sfn|Zuckerman|Hagen|1989|p=31}}{{sfn|Kugler|Keller|1985|pp=112, 192–193}}

In addition, there exist analogous molecules involving [[pseudohalogen]]s, such as the [[cyanogen halide]]s.