Titanium(III) iodide

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:

$\mathrm{2}\mathrm{T}\mathrm{i}\mathrm{+}\mathrm{3}{\mathrm{I}}_{\mathrm{2}}\mathrm{⟶}\mathrm{2}\mathrm{T}\mathrm{i}{\mathrm{I}}_{\mathrm{3}}$

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.