| Abstract: | The interaction between ethylenediamine-di(o-hydroxyphenylacetic acid) (EDDHA, H4Z) and tripositive lanthanide ions has been investigated. The formation constants of the protonated chelates (LnHZ) and those of the normal chelates (LnZ?) have been evaluated at various temperatures and at a constant ionic strength of 0.1(KNO1). For LnHZ, the pH-titrimetric technique, and for LnZ?, the mercury indicator electrode method were used. The enthalpy and entropy changes characterizing the formation of LnZ? have been calculated at 25° and, these functions have been compared with the corresponding values of other lanthanide chelates with related chelating agents. |
