Reduction of Perrhenate by Stannous Tin

Abstract

rhenium, colorimetrically, is based upon the formation of rhenium thiocyanate complex, or complexes, when acidic solutions of perrhenate are reduced by stannous chloride in the presence of excess alkali thiocyanate. The color developed in the solution varies from yellow to orange-red, and absorption or transmission measurements are usually made on the absorption band of 430 m/ wavelength. Because of the instability of the reduced aqueous perrhenate solution, the colored thiocyanate complex must be extracted into an organic solvent (usually ethyl ether) for colorimetric measurements. In this test the oxidation state of rhenium in its colored