Chromium(III) iodide
Chemical compound
From Wikipedia, the free encyclopedia
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 iodides.[3]
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| Names | |
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| IUPAC name
Chromium(III) iodide | |
| Other names
Chromium triiodide, chromic iodide | |
| Identifiers | |
3D model (JSmol) |
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| ChemSpider | |
| ECHA InfoCard | 100.033.614 |
| EC Number |
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PubChem CID |
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CompTox Dashboard (EPA) |
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| Properties | |
| CrI3 | |
| Molar mass | 432.7095 g·mol−1 |
| Appearance | black solid |
| Density | 5.32 g/cm3[1] |
| Melting point | > 600 °C (1,112 °F; 873 K) |
| Soluble | |
| Hazards | |
| GHS labelling:[2] | |
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| Danger | |
| H301, H314 | |
| P260, P264, P264+P265, P270, P280, P301+P316, P301+P330+P331, P302+P361+P354, P304+P340, P305+P354+P338, P316, P317, P321, P330, P363, P405, P501 | |
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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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.[4]
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.[3]
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.[3]
Chromium triiodide can also be prepared as colloidal nanoplatelets, a type of lateral nanostructure. The alkoxide Cr(OC(CH3)(C(CH3)3)2)3 is dissolved in toluene under an inert atmosphere, followed by the addition of trimethylsilyl iodide.[5] The mixture is sealed and immersed into a preheated oil bath at 135 °C, resulting in the formation of a black precipitate.[5]
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.[6]
