Chromium(III) iodide explained

Chromium(III) iodide, also known as chromium triiodide, is an inorganic compound with the formula . It is a black solid that is used to prepare other chromium iodides.[1]

Like the isomorphous chromium(III) chloride, chromium(III) iodide exhibits a cubic-closest packing arrangement in a double-layer crystal lattice. In this structure, chromium exhibits octahedral coordination geometry.[2]

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:

To obtain high purity samples, the product is thermally decomposed at 700 °C to sublime out chromium(II) iodide. The diiodide is then reiodinated.[1]

Chromium triiodide is stable in contact with oxygen and moisture, but at temperatures approaching 200 °C it reacts with oxygen and releases iodine. Like, 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.[1]

Chromium triiodide can also be prepared as nanoplatelets from the alkoxide .[3]

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.[4]

Notes and References

  1. Book: Gregory. N. W.. Handy. L. L.. Inorganic Syntheses . Chromium (III) Iodide . . 1957. 5. 128–130. 10.1002/9780470132364.ch34 .
  2. 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 . 10.1021/ja01124a009 .
  3. 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. 10.1021/acs.nanolett.0c00102. 32031382 . 1530-6984. 2001.04594. 2020NanoL..20.2100D . 210473134 .
  4. Huang. B.. etal . Layer-dependent ferromagnetism in a van der Waals crystal down to the monolayer limit. Nature. 2017. 546. 7657. 270–273. 10.1038/nature22391. 28593970. 1703.05892. 2017Natur.546..270H. 4456526.