Solution chemistry of element 105. Pt. 2. Hydrolysis and complex formation of Nb, Ta, Ha and Pa in HCl solutions

摘要

Calculations of the electronic structure of hydrolyzed species of Nb, Ta, Pa and element 105, Ha, and of their various complexes formed in HCl solutions have been performed using the Dirac-Slater Discrete Variational method. On the basis of results of these calculations, relative values of the free energy change of reactions of complex formation have been determined. The order of the complex formation above 4 M HCl was found to be Pa>>Nb>Ha>Ta. Such a sequence is defined by a predominant electrostatic energy of the metal-ligand interaction. The hydrolysis of compounds, as a reverse process, proved to change as Ta>Ha>Nb>>Pa, which is different from the hydrolysis of cations obeying the sequence Nb>Ta>Ha>>Pa. Using the theory of metal extraction by anion exchange, the following trend in the extraction of the anionic species from the aqueous solutions above 4M HCl has been predicted: Pa>>Nb(>=)Ha>Ta. (orig.)