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The redox properties of the tri-heteropolytungstosilicates of transition elementsK_nSiZ(H_2O)W_(11)O_(39) (Z = Mn~(2+), Fe~(3+), Co~(2+), Ni~(2+), Zn~(2+), Cd~(2+)). In solution have been studied withpolarography and cyclic voltammetry as well as with ultraviolet spectroscopy and X-ray photoelectronspectroscopy. The order of the polarographic half-wave potentials (E_(1/2)) of these heteropolyanions isas follows: Z = Ni~(2+)>Co~(2+)>Zn~(2+)>Fe~(2+)>Mn~(2+). We have found that the E_(1/3) of heteropolyanionscould be correlated linearly with both the electronegativities X of the transition elements and the loga-rithm of the rate constants (log k_e) of reaction of transition metal ions with hydrated electrons. Thereduction mechanism and effects of transition elements on the redox properties of the heteropolyanionshave been discussed.
The redox properties of the tri-heteropolytungstosilicates of transition elements K_nSiZ (H 2 O) W 11 O 39 (Z = Mn 2+, Fe 3+, Co 2+, Ni 2+ The solution of the polarographic half-wave potentials (E_ (1/2)) of these heteropolyanions is as follows: Z = Ni ~ (2 +)> Co ~ (2 +)> Zn ~ (2 +)> Fe ~ (2 +)> Mn ~ have found that the E_ (1/3) of heteropolyanions can be correlated linearly with both the electronegativities X of the transition elements and the loga-rithm of the rate constants (log k_e) of reaction of transition metal ions with hydrated electrons. The reduction mechanism and effects of transition elements on the redox properties of the heteropolyanionshave been discussed.