COMPLEX TELLURATES OF COBALT AND MANGANESE

Abstract

Complex tellurates of manganese and cobalt have been prepared by oxidizing mixtures of manganous or cobaltous sulphate with potassium (or sodium) tellurate by means of an alkaline hypochlorite solution. Cobalt gives K3H6Co(TeO6)2•2H2O as a dark green powder. The formula was confirmed by its oxidation equivalent with ferrous sulphate, by its displacement of chloride ions from an anion exchange resin, and by its magnetic susceptibility (−154 × 10−6 e. m. u./g-mol). The behavior of the compound on acidification is reported. Manganese gives K6H8Mn(TeO6)3•5H2O and Na7H7Mn(TeO6)3•5H2O as dark red crystals. The formula was confirmed as for the cobalt complex: its magnetic moment is 3.30 Bohr magnetons, which is reasonable for Mn(IV). The acid–base properties of the compound were examined. The ion is not very stable in solution, as shown by changes in its absorption spectrum; measurements of this gave evidence for the nature of the decomposition, and the equilibrium constant for this reaction. The main reaction is[Formula: see text]for which K = 4 × 10−5 (g-mol/I.)2 at 25 °C.