The chemistry of superheavy elements. III. Theoretical studies on element 113 compounds

Abstract

The chemistry of element 113 is investigated by theoretical methods. The results of fully relativistic calculations for ͑113͒H and ͑113͒F are compared with those derived by other techniques to obtain an indication of the accuracy of the more approximate models as well as the importance of including scalar and/or spin-orbit relativistic effects. Both of these effects are found to be important. The spin-orbit coupled pseudopotential approximation yields results of satisfactory accuracy, but the two relativistic methods that do not include spin-orbit coupling ͑Douglas-Kroll and scalar relativistic pseudopotential method͒ do not agree so well with each other. The calculated properties of ͑113͒H and ͑113͒F and a number of other hydrides and halides of element 113 are compared with the properties of the equivalent compounds of the lighter group 13 elements. In general, element 13 exhibits behavior that is consistent with its placement in group 13 of the periodic table. Some of its properties are found to be somewhat unusual however, e.g., the element is relatively electronegative, the molecules (113)H 3 , (113)F 3 , and (113)Cl 3 are predicted to be T-shaped rather than trigonal planar, and the 6d electrons of element 113 participate to a significant extent in chemical bonding. Compounds where element 113 is present in the ϩ5 oxidation state are considered as well but are predicted to be thermodynamically unstable.

Relativistic electronic structure studies on the heaviest elements

“…RECP calculations for the reactions M + F 2 → MF 2 and MF 2 + F 2 → MF 4 , where M = Xe, Rn and element 118, indicated the increasing stability of the 2+ and 4+ oxidation states in the group [44,145]. The following trends in the stability of the fluorides were established: RnF 2 < HgF 2 < PbF 2 , while 112F 2 < 114F 2 < 118F 2 .…”

“…PP, DCB, RECP and 4c-DFT calculations for group-13 MF have given increasing R e and μ e from TlF to 113F, in contrast to the decreasing values from TlH to 113H [112,145,146]. DF calculations for (113)(117) [152] revealed a reversal of the dipole direction and a change of the sign of the dipole moment as compared to the other group-13 homologs.…”

“…The stable high-coordination compound 113F 6 − with the metal in the 5+ oxidation state is foreseen. 113F 5 will probably be unstable [145]. The calculated energies of the decomposition reaction MX 3 → MX + X 2 (M = B, Al, Ga, In, Tl to element 113, X = H, F, Cl) suggest a decrease in the stability of the 3+ oxidation state in this group.…”

“…DF calculations for (113)(117) [152] revealed a reversal of the dipole direction and a change of the sign of the dipole moment as compared to the other group-13 homologs. PP and RECP calculations [145,146,148] for 113X 3 (X = H, F, Cl, Br and I) have given the trigonal planar geometric configuration in difference to the homologs showing that the valence shell electron pair repulsion (VSERP) theory is not applicable to the heaviest elements. The stable high-coordination compound 113F 6 − with the metal in the 5+ oxidation state is foreseen.…”

Relativistic calculations on thallium hydride

“…The various computational results for this system have been reviewed by Hess and Marian [3]. In a recent article Seth et al [4] reported results from correlated relativistic four-component calculations using a coupled-cluster wavefunction with single and double excitations and an estimated triples correction [CCSD(T) [5]]. These results must be regarded as representative of the highest obtainable accuracy available up to now.…”