Theoretical examination of covalency in berkelium(IV) carbonate complexes

Abstract

Experimental studies on the speciation of berkelium in carbonate media have shown that complexation of berkelium(III) by carbonate results in spontaneous oxidation to berkelium(IV) and that multiple species can be present in solution. We studied two proposed structures present in solution based on theoretical comparisons with spectroscopic data previously reported for Bk(IV) carbonate solutions. The multiconfigurational character of the ground and low‐lying excited states in both complexes is demonstrated to result from the strong spin‐orbit coupling. Although bonding in Bk(IV) carbonate and carbonate‐hydroxide complexes is dominated by strong Coulombic forces, the presence of non‐negligible covalent character is supported by ligand‐field theory, natural localized orbitals, topological studies of the electron density, and energy transition state natural orbitals for chemical valence. Bond orders based on natural localized molecular orbitals show that BkOH bonds possess enhanced orbital overlap, which is reflected in the bond strength. This is also observed in the decomposition of the orbital interaction energy into individual deformation density pairs.

Theoretical Study of Actinide Complexes with Macropa

“…The overall stabilities of the gas-phase complexes, expressed by the Gibbs free energies of dissociation to M 3+ + L 2– (Table ), are determined by an interplay of covalent (CT by spatial orbital overlap and energy-degeneracy-driven covalency, ,− the latter difficult to estimate quantitatively) and ionic interactions as well as the strain energy of L 2– in the complex. The lowest stability of the Ac­(L) + molecule is in agreement with the rather weak CT interactions, which seemingly could not efficiently be compensated by the stronger ionic interactions and the weakest ligand strain in this complex.…”

Study of Aqueous Am(III)-Aliphatic Dicarboxylate Complexes: Coordination Mode-Dependent Optical Property and Stability Changes

“…To understand the bonding and electronic properties of the optimized structures, topology analyses, including the Wiberg bond index (WBI), were performed using the quantum theory of atoms in molecules (QTAIM) with Multiwfn Code . In addition, Weinhold natural population analysis (NPA) and NBO analysis, including NLMO (natural localized molecular orbital) studies, were performed using NBO 7 …”

“…Figure 9(a) shows that the WBI has much better correlation with the primary formation constant, as expected from the correlation between the WBI and bond strength. In addition, to compare the other computed values related to the bond order, natural localized molecular orbital (NLMO) analysis was performed, 26 which includes the contribution of antibonding to the bond order prediction. The bond orders in NLMO also showed good correlation with the primary formation constants as presented in Figure 9(a).…”

“…25 In addition, Weinhold natural population analysis (NPA) and NBO analysis, including NLMO (natural localized molecular orbital) studies, were performed using NBO 7. 26…”

Electronic structure of Rf+ (Z=104) from ab initio calculations

“…( 2), the effective Hamiltonian can be simply parametrized by the Slater-Condon integrals (F k and G k ) and spin-orbit coupling constants (ζ i ) [51], which allows us to operate the CI algorithm in a semiempirical manner. We note, however, that the parameters can be numerically evaluated, and there are numerous examples in the literature for dealing with lanthanides [51,53,54] or heavier actinide elements [55][56][57]. For the Hf + and Rf + ions, we constructed the effective Hamiltonian with N = 3 electrons in the s, d, and p valence orbitals.…”