Chromium(II) iodide

Chromium(II) iodide is the inorganic compound with the formula CrI₂. It is a red-brown^[1] or black solid. The compound is made by thermal decomposition of chromium(III) iodide. Like many metal diiodides, CrI₂ adopts the "cadmium iodide structure" motif, i.e., it features sheets of octahedral Cr(II) centers interconnected by bridging iodide ligands. Reflecting the effects of its d⁴ configuration, chromium's coordination sphere is highly distorted.^[1][2][3]

Chromium(II) iodide

Names
Other names chromous iodide
Identifiers
CAS Number	13478-28-9
3D model (JSmol)	Interactive image
ChemSpider	13318420
PubChem CID	18626753
CompTox Dashboard (EPA)	DTXSID20595261
InChI InChI=1S/Cr.2HI/h;2*1H/q+2;;/p-2 Key: BMSDTRMGXCBBBH-UHFFFAOYSA-L
SMILES [Cr+2].[I-].[I-]
Properties
Chemical formula	CrI2
Molar mass	305.8050 g·mol−1
Appearance	black deliquescent solid
Density	5.196 g/cm3
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). Infobox references

Treatment of chromium powder with concentrated hydroiodic acid gives a blue hydrated chromium(II) iodide, which can be converted to related acetonitrile complexes.^[4]

Cr + n H₂O + 2 HI → CrI₂(H₂O)_n + H₂