Vanadium Oxytribromide, VOBr₃

Vanadium Oxytribromide, VOBr₃, is produced when pure, dry bromine is passed over vanadous oxide, V₂O₃, heated to redness. Yellowish-white vapours are evolved which condense to a deep red, hygroscopic liquid, density 2.9673 at 0° C. It decomposes slowly at ordinary temperatures into vanadyl dibromide and bromine, but distils without decomposition at 130° to 136° C. under 100 mm. pressure. It is much less stable than vanadyl dibromide, VOBr₂.

An oxybromide of possible constitution VO₂Br₃.5H₂O is known, but the constitution of this compound is a matter of doubt. It is obtained by dissolving hypovanadic oxide, VO₂, in dilute aqueous hydrobromic acid. Hydrochloric acid under similar conditions yields the compound VO₂Cl₂.8H₂O.