Tungsten Pentachloride, WCl₅

Tungsten Pentachloride, WCl₅, is obtained by distillation in carbon dioxide of the lower chlorides produced by reduction of the hexachloride with hydrogen. It is, in the amorphous state, a greyish substance, while its vapour is greenish yellow; in the crystalline condition it forms brilliant black needles. Tungsten pentachloride melts at 248° C. and boils at 275.6° C.; its vapour density is normal. It is hygroscopic, but is decomposed by excess of water, with production of the blue oxide and hydrogen chloride. Upon electrolysis of an alcoholic solution of tungsten pentachloride, the compound WCl₂(OEt)₃, containing pentavalent tungsten, is obtained. Potassium and rubidium compounds, of composition R₂WOCl₅, probably containing pentavalent tungsten in a complex anion, have been described.