Synthesis and Properties of Heteropoly Tungstovanadogermanic Complexes with Rare Earths

Ten tungstovanadogermanic complexes K13H2[Ln(GeW10VO39)2]nH2O (Ln=La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Yb) were synthesized for the first time. Their structures were characterized by IR, UV, ESR, XPS, XRD and magnetic susceptibility. Their redox properties were studied by means of cyclic voctammetry and polargraphy. The results show that the complexes undergo three step reduction, the first step is the double electronic reversible, while the second and the third steps are irreversible. Their thermal stability studied by TG-DTA, IR and XRD at various temperature shows that the range of pyrolysis temperature is 450～500 ℃. The complex stability in solution investigated by the acid-alkali titration indicates that the range of pH in which the heteropoly anions can exist stably is pH=3.3～7.6 at room temperature.