Chromium(II) iodide

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

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]

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

References

^ ^a ^b Greenwood, Norman N.; Earnshaw, Alan (1997). Chemistry of the Elements (2nd ed.). Butterworth-Heinemann. pp. 1019–1022. ISBN 978-0-08-037941-8.
^ Tracy, J. W.; Gregory, N. W.; Stewart, J. M.; Lingafelter, E. C. (1962). "The Crystal Structure of Chromium(II) Iodide". Acta Crystallographica. 15 (5): 460–463. doi:10.1107/S0365110X62001152.
^ Vest, Brian; Hermann, Andreas; Boyd, Peter D. W.; Schwerdtfeger, Peter (2010). "Nucleation of Antiferromagnetically Coupled Chromium Dihalides: From Small Clusters to the Solid State". Inorganic Chemistry. 49 (7): 3169–3182. doi:10.1021/ic901949a.
^ Holah, David G.; Fackler, John P. (1967). "Chromium(II) Salts and Complexes". Inorganic Syntheses: 26–35. doi:10.1002/9780470132418.ch4.

[G&E-1] Greenwood, Norman N.; Earnshaw, Alan (1997). Chemistry of the Elements (2nd ed.). Butterworth-Heinemann. pp. 1019–1022. ISBN 978-0-08-037941-8.

[2] Tracy, J. W.; Gregory, N. W.; Stewart, J. M.; Lingafelter, E. C. (1962). "The Crystal Structure of Chromium(II) Iodide". Acta Crystallographica. 15 (5): 460–463. doi:10.1107/S0365110X62001152.

[3] Vest, Brian; Hermann, Andreas; Boyd, Peter D. W.; Schwerdtfeger, Peter (2010). "Nucleation of Antiferromagnetically Coupled Chromium Dihalides: From Small Clusters to the Solid State". Inorganic Chemistry. 49 (7): 3169–3182. doi:10.1021/ic901949a.

[4] Holah, David G.; Fackler, John P. (1967). "Chromium(II) Salts and Complexes". Inorganic Syntheses: 26–35. doi:10.1002/9780470132418.ch4.

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