Rare earth complexonates with anomalous oxidation states

Rare earth complexonates are investigated in unusual oxidation states (2+ and 4+). The possibilities of Ce(4), Pr(4) and Tb(4) stabilization are studied using the method of complexing in aqueous solutions. It is shown that Pr(4) and Tb(4) compounds in aqueous solution are unstable and can not be stabilized using the method of complexing. The analysis of results of investigating the kinetics of oxidation reduction interaction in the Ce(4)-complexone (NTA, EDTA, HEDTA, HDTTA) system depending on the solution pH, ligand concentration and the nature of an inorganic anion, has shown that Ce(4) reduction with a complexone can take place only in the case of its direct contact with a non-complexes ligand. However, if Ce(4) forms a stable coordinately-saturated complexonate, its reduction does not occur. The polarographic and pH-potentiometric methods have been used to investigate Eu(2) complexonates with EDTA, CDTA, DTPA... The stability constants of compounds are presented