SOLVENT EFFECTS ON THE REDOX POTENTIALS OF POTASSIUM 12-TUNGSTOSILICATE AND 18-TUNGSTODIPHOSPHATE

To our knowledge, hexacyanoferrate (III) and hexacyanomanganate (III) are the best representative cases for the study of solvent effects on redox potentials of anions. To enlarge examples in this field, it is shown here that two heteropolyacid potassium salts, alpha SiW//1//2O//4//0K//4 and alpha P//2W//1//8O//6//2K//6, as studied by slow sweep rate cyclic voltammetry, undergo reversible or quasi-reversible reduction in several solvents. The specific interactions between solvents and the nitrogen atoms of the hexacyano complexes are replaced by interactions with oxygen atoms. The redox potentials, in the present cases, are also found to be functions of the acceptor number of the solvents.