Heterogeneous catalysis in solution. Part IX. Reduction of bromopenta-amminecobalt(III) and other cobalt(III) complexes in the presence of solids

Abstract

Co(NH₃)₅Br²⁺ in aqueous acid solution reacts more rapidly in the presence of various solids. The only effect of platinized platinum is to cause reduction of the complex to cobalt(II). With mercury(II) sulphide or silver(I) bromide present, a significant fraction of the enhanced rate is due to reduction. Addition of charcoal in various forms brings about partial reduction of aqueous Co(NO₂)₆^3– and of aqueous ammoniacal Co(NH₃)₆³⁺.