Vanadium(III) iodide is the

inorganic compound In chemistry, an inorganic compound is typically a chemical compound that lacks carbon–hydrogen bonds, that is, a compound that is not an organic compound. The study of inorganic compounds is a subfield of chemistry known as '' inorganic chemist ...

with the formula VI₃. This paramagnetic solid is generated by the reaction of

vanadium Vanadium is a chemical element with the symbol V and atomic number 23. It is a hard, silvery-grey, malleable transition metal. The elemental metal is rarely found in nature, but once isolated artificially, the formation of an oxide layer ( pas ...

powder with

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

at around 500 °C. The black hygroscopic crystals dissolve in water to give green solutions, characteristic of V(III) ions. The purification of vanadium metal by the chemical transport reaction involving the reversible formation of vanadium(III) iodides in the presence of

and its subsequent decomposition to yield pure metal: : 2 V + 3 I₂ ⇌ 2 VI₃ VI₃ crystallizes in the motif adopted by bismuth(III) iodide: the iodides are hexagonal-closest packed and the vanadium centers occupy one third of the octahedral holes. When solid samples are heated, the gas contains VI₄, which is probably the volatile vanadium component in the vapor transport method. Thermal decomposition of the triiodide leaves a residue of vanadium(II) iodide: : 2 VI₃ → VI₂ + VI₄ ΔH = 36.6 kcal/mol; ΔS = 38.7 e.u.

References

{{Iodides Iodides Metal halides Vanadium(III) compounds