Indium(III) iodide or indium triiodide is a chemical compound of

indium Indium is a chemical element; it has Symbol (chemistry), symbol In and atomic number 49. It is a silvery-white post-transition metal and one of the softest elements. Chemically, indium is similar to gallium and thallium, and its properties are la ...

and

iodine Iodine is a chemical element; it has symbol I and atomic number 53. The heaviest of the stable halogens, it exists at standard conditions as a semi-lustrous, non-metallic solid that melts to form a deep violet liquid at , and boils to a vi ...

with the formula InI₃.

Preparation

Indium(III) iodide can be obtained by reacting indium with iodine vapor: : Indium(III) iodide can also be obtained by evaporation of a solution of indium in HI.

Properties

Indium(III) iodide is a pale yellow, very hygroscopic

monoclinic In crystallography, the monoclinic crystal system is one of the seven crystal systems. A crystal system is described by three Vector (geometric), vectors. In the monoclinic system, the crystal is described by vectors of unequal lengths, as in t ...

solid (

space group In mathematics, physics and chemistry, a space group is the symmetry group of a repeating pattern in space, usually in three dimensions. The elements of a space group (its symmetry operations) are the rigid transformations of the pattern that ...

''P''2₁''/c'' (space group no. 14), a = 9.837 Å, b = 6.102 Å, c = 12.195 Å, β = 107.69°), which melts at 210 °C to form a dark brown liquid and is highly soluble in water. Its crystals consist of dimeric molecules. The yellow β form slowly converts to the red α form. In the presence of water vapor, the compound reacts with oxygen at 245 °C to form indium(III) oxide iodide. 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 X-ray crystallography is the experimental science of determining the atomic and molecular structure of a crystal, in which the crystalline structure causes a beam of incident X-rays to Diffraction, diffract in specific directions. By measuring th ...

; however, spectroscopic evidence indicates that indium may be six coordinate.Taylor M. J., Kloo L. A. Journal of Raman Spectroscopy 31, 6, (2000), 465 The yellow form consists of In₂I₆ with 4 coordinate indium centres.

References

{{iodides Iodides Indium compounds Metal halides