Hafnium(IV) iodide

{{Chembox

| ImageFile = HfI4.tif

| ImageSize = 270

| ImageAlt =

| IUPACName = Hafnium(IV) iodide

| OtherNames = hafnium tetraiodide, tetraiodohafnium

|Section1={{Chembox Identifiers

| CASNo = 13777-23-6

| PubChem = 83726

| ChemSpiderID = 75548

| EINECS = 621-502-1

| StdInChI=1S/Hf.4HI/h;4*1H/q+4;;;;/p-4

| StdInChIKey = YCJQNNVSZNFWAH-UHFFFAOYSA-J

| SMILES = I[Hf](I)(I)I

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|Section2={{Chembox Properties

| Formula = HfI₄

| MolarMass = 686.11

| Appearance = red-orange

| Density = 5.60 g/cm³{{RubberBible92nd|page=4.66}}

| MeltingPtC = 449

| MeltingPt_ref =

| BoilingPtC = 394

| BoilingPt_notes = (sublimes)

| BoilingPt_ref =

| Solubility = }}

|Section3={{Chembox Structure

| CrystalStruct = Monoclinic, mS40

| SpaceGroup = C2/c, No. 15

| LattConst_a = 1.1787 nm

| LattConst_b= 1.1801 nm

| LattConst_c=1.2905 nm

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|Section4={{Chembox Hazards

| MainHazards =

| FlashPt =

| AutoignitionPt = }}

|Section8={{Chembox Related

| OtherCompounds = Hafnium(III) iodide

| OtherAnions = Hafnium(IV) fluoride
Hafnium(IV) chloride
Hafnium(IV) bromide

| OtherCations = Titanium(IV) iodide
Zirconium(IV) iodide

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Hafnium(IV) iodide is the inorganic compound with the formula HfI₄. It is a red-orange, moisture sensitive, sublimable solid that is produced by heating a mixture of hafnium with excess iodine. It is an intermediate in the crystal bar process for producing hafnium metal.

In this compound, the hafnium centers adopt octahedral coordination geometry. Like most binary metal halides, the compound is a polymeric. It is one-dimensional polymer consisting of chains of edge-shared bioctahedral Hf₂I₈ subunits, similar to the motif adopted by HfCl₄. The nonbridging iodide ligands have shorter bonds to Hf than the bridging iodide ligands.{{Cite journal | doi = 10.1016/0022-5088(80)90005-3| title = Hafniumtetrajodid HfI₄: Struktur und eigenschaften. Ein neuer AB₄-strukturtyp| journal = Journal of the Less Common Metals| volume = 76| pages = 7–16| year = 1980| last1 = Krebs | first1 = B. | last2 = Sinram | first2 = D. | issue = 1–2}}