Determination of rhenium based on the formation of rhenium(VI) oxide halide complexes by spectrophotometry and electron spin resonance spectroscopy

Abstract

The possibility of obtaining solutions of rhenium(VI) compounds and their analytical applications has been studied. The rhenium(VI) compounds formed, ReOCl₅^– and ReOBr₄, are characterised by specific absorbance spectra and electron spin resonance (ESR) spectra. New quantitative methods of rhenium determination were devised. The formation of ReOBr₄ in sulphuric acid from the ReO₄^– ion and KBr was used for the development of a selective spectrophotometric method for the determination of rhenium and the ability of ReOBr₄ to be extracted into organic solvents was used for rhenium determination by ESR.

On the basis of ReOCl₅^– formation, a quantitative method for the determination of rhenium by the spectrophotometric titration of ReO₄^– in a mixture of sulphuric and hydrochloric acids using an iron(II) solution was devised. The methods were also applied to alloys.