The electronic structure of the actinide oxides and their singly and doubly charged cations: A ligand field approach

Abstract

Ligand field theory (LFT) calculations of energy levels were performed for the neutral actinide monooxides (AnO) and their singly and doubly ionized cations (AnO+ and AnO2+) by treating the molecular electronic states as Anm+ free‐ion energy levels (where An ∈ Th through Lr and m = 1, 2, 3, or 4) perturbed by the electric field of O2−or O−. LFT parameters obtained from fits to the energy levels of ThO, ThO+, UO, and UO+ were used to compute molecular energy levels for the lowest energy (maximum Sc, maximum Lc) 5f‐core states of An4+, An3+, An2+, and An+ for the majority of the An4+O2−, An3+O−, An3+O2−, An2+O−, An2+O2−, and An+O− electronic configurations. Simple linear relationships enabled predictions of the dissociation energies for AnO, AnO+ and AnO2+ (where An ∈ Bk through Lr) and ionization energies for AnO and AnO+ (where An ∈ Bk through Lr), mainly based on recent accurate experimental data for the ionization energies of An atoms (where An ∈ Fm, Md, No, and Lr) and correlations with the energetics of the atoms and ions.

Bond Dissociation Energies Reveal the Participation of d Electrons in f-Element Halide Bonding

“…Various types of perturbations, such as in ligand field theory (LFT), have been applied to species such as ionic lanthanide halides to rationalize their properties, including BDEs. ,− An underlying precept of LFT and related treatments of ionic molecules is that the metal ion largely retains its atomic character but is perturbed by the anion, enabling the prediction of molecular properties from those of the constituent atoms. We employ the inverse of this tactic to deduce from the molecular property, specifically that of BDE, which atomic orbitals participate in bonding.…”

Electronic Configuration Assignments for UO from Electric Dipole Moment Measurements

“…The formal oxidation states given here are clearly too ionic, but the indicated occupations of the metal-centered orbitals appear to be valid. This conclusion is implied by the success of ligand field theory (LFT) in predicting the low-energy states of UO ,, and UO +9, . Due to the presence of partially filled f -orbitals, the densities of electronic states for these molecules are high …”

“…This conclusion is implied by the success of ligand field theory (LFT) in predicting the low-energy states of UO ,, and UO +9, . Due to the presence of partially filled f -orbitals, the densities of electronic states for these molecules are high …”

“…A valuable facet of the LFT model is that it illuminates a spectroscopic approach that can be used to recognize states that arise from a common electronic configuration. ,,− Because the metal-centered 5 f and 7 s orbitals are not substantially involved in the bonding, states derived from a given metal-ion configuration should have closely similar vibration and rotation constants. For the example of UO, it is predicted that the states of the 5 f 2 7 s 2 configuration will have larger characteristic vibrational and rotational constants than the characteristic values for the states from the 5 f 3 7 s configuration.…”

“…26 Due to the presence of partially filled forbitals, the densities of electronic states for these molecules are high. 9 A valuable facet of the LFT model is that it illuminates a spectroscopic approach that can be used to recognize states that arise from a common electronic configuration. 4,9,25−27 Because the metal-centered 5f and 7s orbitals are not substantially involved in the bonding, states derived from a given metal-ion configuration should have closely similar vibration and rotation constants.…”