Titanium(III) iodide explained

Titanium(III) iodide is an inorganic compound with the formula TiI₃. It is a dark violet solid that is insoluble in solvents, except upon decomposition.

Preparation and structure

Titanium(III) iodide can be prepared by reaction of titanium with iodine:^[1]

2 Ti+3 I _{2} \longrightarrow2 TiI _{3} It can also be obtained by reduction of TiI₄, e.g., with aluminium.

In terms of its structure, the compound exists as a polymer of face-sharing octahedra. Above 323 K, the Ti---Ti spacing are equal, but below that temperature, the material undergoes a phase transition. In the low temperature phase, the Ti---Ti contacts are alternating short and long. The low temperature structure is similar to that of molybdenum tribromide.^[2]

References

1. F. Hein, S. Herzog "Molybdenum(III) Bromide" in Handbook of Preparative Inorganic Chemistry, 2nd Ed. Edited by G. Brauer, Academic Press, 1963, NY. Vol. 1. p. 1407.
2. Joachim. Angelkort. Andreas. Schoenleber. Sander. van Smaalen. Low- and High-Temperature Crystal Structures of TiI₃. Journal of Solid State Chemistry. 182. 2009. 3 . 525–53. 10.1016/j.jssc.2008.11.028. 2009JSSCh.182..525A . .