Tantalum Trichloride, TaCl₃

Tantalum Trichloride, TaCl₃, is prepared by reducing the pentachloride with aluminium in the presence of aluminium chloride and heating the product to between 350° and 400° C. It is a dark green substance which yields intensely green aqueous solutions without evolution of hydrogen. These solutions are fairly stable, and oxidise only slowly on being exposed to air; the rate of oxidation is accelerated by the presence of alkali and checked by the addition of acids.