iodine trichloride

{{chembox

| Watchedfields = changed

| verifiedrevid = 446239317

| ImageFile = Iodine trichloride.svg

| ImageName = Full structural formula of the dimer

| ImageSize = 140

| ImageFile1 = Iodine-trichloride-dimer-3D-vdW.png

| ImageSize1 = 160

| ImageName1 = Space-filling model of the dimer

| ImageFile2 = Iodine trichloride cropped.jpg

| ImageSize2 = 180

| ImageName2 = Commercial sample of iodine trichloride

| IUPACName = Iodine trichloride

| OtherNames = Diiodine hexachloride

|Section1={{Chembox Identifiers

| ChemSpiderID_Ref = {{chemspidercite|correct|chemspider}}

| ChemSpiderID = 63265

| InChI = 1/Cl3I/c1-4(2)3

| InChIKey = PAWIVBWALDNUJP-UHFFFAOYAF

| StdInChI_Ref = {{stdinchicite|correct|chemspider}}

| StdInChI = 1S/Cl3I/c1-4(2)3

| StdInChIKey_Ref = {{stdinchicite|correct|chemspider}}

| StdInChIKey = PAWIVBWALDNUJP-UHFFFAOYSA-N

| CASNo_Ref = {{cascite|correct|??}}

| CASNo = 865-44-1

| UNII_Ref = {{fdacite|correct|FDA}}

| UNII = 1E5KQ66TRQ

| PubChem = 70076

| SMILES = ClI(Cl)Cl

| SMILES_Comment = monomer

| SMILES1 = Cl[I-]1(Cl)[Cl+][I-]([Cl+]1)(Cl)Cl

| SMILES1_Comment = dimer

}}

|Section2={{Chembox Properties

| Formula = I₂Cl₆

| MolarMass = 466.5281 g/mol

| Appearance = yellow solid

| Density = 3.11 g/cm³

| MeltingPtC = 63

| BoilingPt =

| Solubility =

| MagSus = {{val|-90.2e-6|u=cm³/mol}}}}

|Section3={{Chembox Hazards

| MainHazards =

| FlashPt =

| AutoignitionPt =

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Iodine trichloride is an interhalogen compound of iodine and chlorine. It is bright yellow but upon time and exposure to light it turns red due to the presence of elemental iodine. In the solid state is present as a planar dimer I₂Cl₆, with two bridging Cl atoms.{{cite journal | author1 = K. H. Boswijk | author2 = E. H. Wiebenga | year = 1954 | title = The crystal structure of I₂Cl₆ (ICl₃) | journal = Acta Crystallographica | volume = 7 | issue = 5| pages = 417–423 | doi = 10.1107/S0365110X54001260 | doi-access = free }}

It can be prepared by reacting iodine with an excess of liquid chlorine at −70 °C, or heating a mixture of liquid iodine and chlorine gas to 105 °C.{{cn|date=July 2024}} In the molten state it is conductive, which may indicate dissociation:{{Greenwood&Earnshaw}}

:I₂Cl₆ {{eqm}} {{chem|ICl|2|+}} + {{chem|ICl|4|−}}

It is an oxidizing agent, capable of causing fire on contact with organic materials.{{cn|date=November 2024}} That oxidizing power also makes it a useful catalyst for organic chlorination reactions.{{cite book|title=Catalysis in Organic Chemistry|first=Paul|last=Sabatier|translator-first=E. Emmet|translator-last=Reid|location=New York, NY|publisher=Van Nostrand|year=1922|p=2|url=https://www.sciencemadness.org/library/books/catalysis_in_organic_chemistry.pdf}}

Iodine trichloride reacts with concentrated hydrochloric acid, forming tetrachloroiodic acid:{{Cite journal |last=Bateman |first=Richard J. |last2=Bateman |first2=Linda R. |date=February 1972 |title=Solid-state structure, nuclear quadrupole resonance spectrum, and the resultant symmetry implications for tetrachloroiodic acid tetrahydrate |url=https://pubs.acs.org/doi/abs/10.1021/ja00759a017 |journal=Journal of the American Chemical Society |language=en |volume=94 |issue=4 |pages=1130–1134 |doi=10.1021/ja00759a017 |issn=0002-7863|url-access=subscription }}

:ICl₃ + HCl → HICl₄