The Catalytic Effect of Osmium Compounds on the Reduction of Perchloric Acid by Hydrobromic Acid

In a previous communication it was shown that the reduction of perchloric acid by hydrobromic acid was catalyzed by trivalent ruthenium salts, and a mechanism for the catalyzed reaction was proposed. Because of the similarity of the oxidation states of ruthenium and osmium it was thought that osmium compounds might behave in a similar manner. Preliminary experiments showed that the reaction is catalyzed by osmium tetroxide, K_2OsO_4•2H_2O, K_2OsBr_6 and K_3OsBr_6, although the effect is much less than in the case of ruthenium.