COMPLEX MANGANESE PERIODATES

Abstract

The preparation of complex periodatomanganates, from manganous salts reacting with sodium (or potassium) hypochlorite and periodate, is described. The products were Na7H4Mn(IO6)3.17H2O and K7H4Mn(IO6)3.8H2O. The manganese was shown to be tetravalent from its redox equivalent in its reaction with iodide and with ferrous ions, and from its magnetic moment, which was 3.87 Bohr magnetons, corresponding to three unpaired electron spins. The ion has an absorption maximum at 483 mμ. Rather complicated pH curves were found for this compound in acid-base titrations. The complex ion decomposes slowly to permanganate and iodate; the kinetics of this reaction have been measured, and a possible mechanism has been suggested. The reaction proceeds in several steps by way of simpler complex ions. The same applies to the reaction between iodide ions and the complex ions when the pH is about 9.