Indium(III) iodide explained

Indium(III) iodide or indium triiodide is a chemical compound of indium and iodine with the formula InI₃.

Preparation

Indium(III) iodide can be obtained by reacting indium with iodine vapor:^[1]

Indium(III) iodide can also be obtained by evaporation of a solution of indium in HI.^[2]

Properties

Indium(III) iodide is a pale yellow, very hygroscopic monoclinic solid (space group P2₁/c (space group no. 14), a = 9.837 Å, b = 6.102 Å, c = 12.195 Å, β = 107.69°),^[3] which melts at 210 °C to form a dark brown liquid and is highly soluble in water. Its crystals consist of dimeric molecules.^[4] The yellow β form slowly converts to the red α form.^[5] In the presence of water vapor, the compound reacts with oxygen at 245 °C to form indium(III) oxide iodide.^[6]

Distinct yellow and red forms are known. The red form undergoes a transition to the yellow at 57 °C. The structure of the red form has not been determined by X-ray crystallography; however, spectroscopic evidence indicates that indium may be six coordinate.^[7] The yellow form consists of In₂I₆ with 4 coordinate indium centres.

Notes and References

1. Book: Handbuch der präparativen anorganischen Chemie. 1 . 1975 . Enke . 978-3-432-02328-1 . 3., umgearb. Aufl . Stuttgart.
2. Book: E. Donges. Indium(III) Iodide. Handbook of Preparative Inorganic Chemistry, 2nd Ed. . G. Brauer. Academic Press. 1963. NY, NY. 1. 861–2.
3. Forrester . J. D. . Zalkin . Allan . Templeton . David H. . Jan 1964 . Crystal and Molecular Structure of Indium(III) Iodide (In 2 I 6) . Inorganic Chemistry . en . 3 . 1 . 63–67 . 10.1021/ic50011a013 . 0020-1669.
4. Book: Handbuch der präparativen anorganischen Chemie. 1 . 1975 . Enke . 978-3-432-02328-1 . 3., umgearb. Aufl . Stuttgart.
5. Book: Downs, Anthony John . Chemistry of aluminium, gallium, indium and thallium . 1993 . Blackie . 978-0-7514-0103-5 . London Glasgow New York [etc.].
6. Book: Hagen, A. P. . Inorganic Reactions and Methods, The Formation of Bonds to Group VIB (O, S, Se, Te, Po) Elements (Part 1) . 2009-09-17 . John Wiley & Sons . 978-0-470-14540-1 . en.
7. Taylor M. J., Kloo L. A. Journal of Raman Spectroscopy 31, 6, (2000), 465