Solution Chemistry of Element 105 Part II: Hydrolysis and Complex Formation of Nb, Ta, Ha and Pa in HCl Solutions

Abstract

Element 105 / Hahnium / Transactinide chemistry / Relativistic molecular calculations / Complex formation SummaryCalculations 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 DiracSlater 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 4 M HCl has been predicted: Pa > Nb a Ha > Ta.

Chemical studies of elements with Z≥ 104 in liquid phase

“…8(a). Thus, the extraction sequence Pa > Nb ≥ Db > Ta is established exactly as theoretically predicted [62,63]. In the system Aliquat 336/HF, the result is depicted in Fig.…”

Chemistry of superheavy elements

“…The interpretation of these results was hampered by the use of mixed HCl/HF solutions. In contrast to the experimental result, the inverse order Pa Nb ≥ Db > Ta was theoretically predicted [196] for pure HCl. This work considered the competition between hydrolysis [197] and chloride complex formation.…”

RESULTS OF THE EXPERIMENT FOR CHEMICAL IDENTIFICATION OF Db AS A DECAY PRODUCT OF ELEMENT 115

“…In the processes of extraction by Aliquat 336 [10] from the chloride solutions, its behavior is most close to that of Nb and differs from Ta and Pa (pseudo-homologue), while in the extraction from the uoride solutions it is analogous to Nb and Ta and differs from Pa. In general, one observes the theoretically predicted [11,12] inversion of the properties within the group of homologues with the transition from 5d to 6d elements, i.e., in its chemical properties Db is most close not to Ta but to Nb. For the chemical identiˇcation, the element should be separated according to its group properties.…”