Research on Characteristics of Transition Elements in Solution. 1. Studies on Rhodium Chemistry. 2. Studies on Ruthenium Chemistry

Abstract : A method is described for the preparation of halogenide-free rhodium (III) perchlorate and sulfate solutions. For the analysis of total Rh, a method is proposed, based on reduction of the metal by passing H2 through the solution at 90 deg C. The filtrate can afterwards be conveniently analyzed for excess H +, for total anions by ion exchanger and for other constituents. Preliminary studies on the hydrolysis of rhodium (III) in perchlorate solutions at 25 deg C, by emf and spectrophotometric measurements, indicate that a single species predominates, probably with 1.75 ! 0.1 OH(-) bound per Rh atom. The experimental conditions were investigated for the quantitative oxidation of Rh(III) to Rh(V) by means of O3 in perchlorate and sulfate solution. Extinction curves for Rh(III) in perchlorate, sulfate and chloride solutions, and for Rh(V) in sulfate and perchlorate solutions are given. Ru(IV) sulfate or perchlorate solution and Ru(III) sulfate solution were prepared by reducing RuO4. A redox titration method is proposed suitable for determining total Ru in dilute solutions.