Hydrated Vanadium Tri-iodide, VI₃.6H₂O

Hydrated Vanadium Tri-iodide, VI₃.6H₂O, is prepared by reducing, electrolytically, a solution of vanadium pentoxide, V₂O₅, in hydriodic acid, until the product becomes green; more hydriodic acid is then added and the whole allowed to stand over lime and concentrated sulphuric acid at 0° C. Small green needles separate, which have the same crystalline form as the hydrated trivalent halides of titanium, iron, and chromium. These crystals are extremely hygroscopic and deliquesce in air to a brown liquid which is extremely unstable.

No definite oxyiodides of vanadium are known, although several substances of varying composition have been obtained by the action of vanadium pentoxide on hydriodic acid.