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
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	432.710 g/mol
Appearance	black solid
Density	5.32 g/cm3[1]
Melting point	> 600 °C (1,112 °F; 873 K)
	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 CrI₃. It is a black solid that is used to prepare other chromium compounds.[2]

Being isomorphous with chromium(III) chloride (CrCl₃), it 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]

At room temperature, 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]

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.
Gregory, N. W., Handy, L. L. "Chromium(III) iodide" Inorg. Synth. 1957, vol. 5, 128-130. doi:10.1002/9780470132364.ch34
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.

This article is issued from Wikipedia. The text is licensed under Creative Commons - Attribution - Sharealike. Additional terms may apply for the media files.

[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. "Chromium(III) iodide" Inorg. Synth. 1957, vol. 5, 128-130. doi:10.1002/9780470132364.ch34

[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.