Chromium(III) iodide

Chromium(III) iodide
Names
	IUPAC name Chromium(III) iodide
	Other names Chromium triiodide, chromic iodide
Identifiers
CAS Number	13569-75-0;
3D model (JSmol)	Interactive image;
ChemSpider	75416;
ECHA InfoCard	100.033.614
EC Number	236-991-3;
PubChem CID	83586;
CompTox Dashboard (EPA)	DTXSID50929111 ;
	InChI InChI=1S/Cr.3HI/h;31H/q+3;;;/p-3 Key: PPUZYFWVBLIDMP-UHFFFAOYSA-K; InChI=1/Cr.3HI/h;31H/q+3;;;/p-3/rCrI3/c2-1(3)4 Key: PPUZYFWVBLIDMP-GXOYXQMQAU;
	SMILES [Cr](I)(I)I;
Properties
Chemical formula	CrI3
Molar mass	432.7095 g·mol−1
Appearance	black solid
Density	5.32 g/cm3
Melting point	> 600 °C (1,112 °F; 873 K)
Solubility in water	Soluble
	Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). Infobox references

Chromium(III) iodide, also known as chromium triiodide, is an inorganic compound with the formula Cr I₃. It is a black solid that is used to prepare other chromium iodides.^[2]

Like the isomorphous chromium(III) chloride (CrCl₃), chromium(III) iodide exhibits a cubic-closest packing arrangement in a double-layer crystal lattice. In this structure, chromium exhibits octahedral coordination geometry.^[3]

Preparation and properties

Chromium triiodide is prepared by the direct reaction of chromium metal with an excess of iodine. The reaction is conducted at 500 °C:

2 Cr + 3 I₂ → 2 CrI₃

To obtain high purity samples, the product is thermally decomposed at 700 °C to sublime out chromium(II) iodide. The diiodide is then reiodinated.^[2]

Chromium triiodide is stable in contact with oxygen and moisture, but at temperatures approaching 200 °C it reacts with oxygen and releases iodine. Like CrCl₃, the triiodide exhibits slow solubility in water owing to the kinetic inertness of Cr(III). Addition of small amounts of chromous iodide accelerates the dissolving process.^[2]

Chromium triiodide can also be prepared as nanoplatelets^{[clarification needed]} from the alkoxide Cr(OC(CH₃)(C(CH₃)₃)₂)₃.^[4]^[how?]

Chromium triiodide was one of the first materials which was discovered to be a magnetic two-dimensional material that has great potentials for spintronics devices.^[5]

References

^ Perry, Dale L. (2011). Handbook of Inorganic Compounds, Second Edition. Boca Raton, Florida: CRC Press. p. 123. ISBN 978-1-43981462-8. Retrieved 2014-01-10.
^ ^a ^b ^c Gregory, N. W.; Handy, L. L. (1957). "Chromium (III) Iodide". Inorganic Syntheses. Vol. 5. pp. 128–130. doi:10.1002/9780470132364.ch34. {{cite book}}: |journal= ignored (help)
^ Gregory, N. W.; Handy, L. L. (1952). "Structural Properties of Chromium(III) Iodide and Some Chromium(III) Mixed Halides". J. Am. Chem. Soc. 74 (4): 891–893. doi:10.1021/ja01124a009.
^ De Siena, Michael C.; Creutz, Sidney E.; Regan, Annie; Malinowski, Paul; Jiang, Qianni; Kluherz, Kyle T.; Zhu, Guomin; Lin, Zhong; De Yoreo, James J.; Xu, Xiaodong; Chu, Jiun-Haw (2020-03-11). "Two-Dimensional van der Waals Nanoplatelets with Robust Ferromagnetism". Nano Letters. 20 (3): 2100–2106. arXiv:2001.04594. Bibcode:2020NanoL..20.2100D. doi:10.1021/acs.nanolett.0c00102. ISSN 1530-6984. PMID 32031382. S2CID 210473134.
^ Huang, B.; et al. (2017). "Layer-dependent ferromagnetism in a van der Waals crystal down to the monolayer limit". Nature. 546 (7657): 270–273. arXiv:1703.05892. Bibcode:2017Natur.546..270H. doi:10.1038/nature22391. PMID 28593970. S2CID 4456526.

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[Handbook-1] Perry, Dale L. (2011). Handbook of Inorganic Compounds, Second Edition. Boca Raton, Florida: CRC Press. p. 123. ISBN 978-1-43981462-8. Retrieved 2014-01-10.

[Greg-2] Gregory, N. W.; Handy, L. L. (1957). "Chromium (III) Iodide". Inorganic Syntheses. Vol. 5. pp. 128–130. doi:10.1002/9780470132364.ch34. {{cite book}}: |journal= ignored (help)

[3] Gregory, N. W.; Handy, L. L. (1952). "Structural Properties of Chromium(III) Iodide and Some Chromium(III) Mixed Halides". J. Am. Chem. Soc. 74 (4): 891–893. doi:10.1021/ja01124a009.

[4] De Siena, Michael C.; Creutz, Sidney E.; Regan, Annie; Malinowski, Paul; Jiang, Qianni; Kluherz, Kyle T.; Zhu, Guomin; Lin, Zhong; De Yoreo, James J.; Xu, Xiaodong; Chu, Jiun-Haw (2020-03-11). "Two-Dimensional van der Waals Nanoplatelets with Robust Ferromagnetism". Nano Letters. 20 (3): 2100–2106. arXiv:2001.04594. Bibcode:2020NanoL..20.2100D. doi:10.1021/acs.nanolett.0c00102. ISSN 1530-6984. PMID 32031382. S2CID 210473134.

[5] Huang, B.; et al. (2017). "Layer-dependent ferromagnetism in a van der Waals crystal down to the monolayer limit". Nature. 546 (7657): 270–273. arXiv:1703.05892. Bibcode:2017Natur.546..270H. doi:10.1038/nature22391. PMID 28593970. S2CID 4456526.

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