Vanadous Fluoride, VF₃

Vanadous Fluoride, vanadium trifluoride, VF₃, is produced when hydrogen fluoride is allowed to react with pure, dry vanadous chloride, VCl₃, at a dark red heat. It is a greenish-yellow powder, almost insoluble in water and the usual organic solvents. It sublimes at a bright red heat. Density at 19° C., 3.3628. The trihydrate, VF₃.3H₂O, separates in dark green rhombohedral crystals when vanadous oxide, V₂O₃, is dissolved in aqueous hydrofluoric acid and the solution is concentrated. This fluoride has also been prepared by the electrolytic reduction of a solution of vanadyl difluoride in hydrofluoric acid.5 It decomposes rapidly, with absorption of oxygen, on exposure to air or in solution. It reduces silver salts to the metal, and mercuric and cupric salts to the mercurous and cuprous state, respectively. With alkali carbonates and hydroxides it reacts to throw down a voluminous greyish-green precipitate of vanadous hydroxide, V(OH)₃, which also oxidises in the air. Vanadous fluoride possesses the property common to many fluorides of forming a large number of easily crystallisable double salts with the fluorides of other metals and with ammonium fluoride.