SOLUTION CHEMISTRY OF ELEMENT-105 - PART-II - HYDROLYSIS AND COMPLEX-FORMATION OF NB, TA, HA AND PA IN HCL SOLUTIONS

Calculations of the electronic structure of hydrolyzed species of Nb, Ta, Pa and element 105, Ha, and of their various complexes formed in H Cl solutions have been performed using the Dirac-Slater Discrete Varia tional method. On the basis of results of these calculations, relative values of the free energy change of reactions of complex formation ha ve been determined. The order of the complex formation above 4M HCl wa s found to be Pa much greater than Nb > Ha > Ta. Such a sequence is de fined by a predominant electrostatic energy of the metal-ligand intera ction. The hydrolysis of compounds, as a reverse process, proved to ch ange as Ta > Ha > Nb much greater than Pa, which is different from the hydrolysis of cations obeying the sequence Nb > Ta > Ha much greater than Pa. Using the theory of metal extraction by anion exchange, the f ollowing trend in the extraction of the anionic species from the aqueo us solutions above 4 M HCl has been predicted: Pa much greater than Nb greater than or equal to Ha > Ta.