All-electron CASPT2 study of Ce(η8–C8H6)2

Kerridge, Andrew; Kaltsoyannis, Nikolas

doi:10.1016/j.crci.2010.02.006

Cited by 23 publications

(26 citation statements)

References 37 publications

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“…Originally characterised as a Ce(IV) compound, [87][88][89] XANES spectroscopy 90 and ab initio calculations 91 supported an alternative interpretation, namely that the complex exhibits a multiconfigurational ground state with B80% Ce(III) character. This surprising result was investigated by the Kaltsoyannis group, 92,93 who reported that the assignment of oxidation state based on configurational admixture was ambiguous. As a result of density based analysis, the authors assigned a +4 oxidation state, but noted significant charge delocalisation which could account for the reported XANES data.…”

Section: Oxidation State Identificationmentioning

confidence: 99%

Quantification of f-element covalency through analysis of the electron density: insights from simulation

2017

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The electronic structure of f-element compounds is complex due to a combination of relativistic effects, strong electron correlation and weak crystal field environments. However, a quantitative understanding of bonding in these compounds is becoming increasingly technologically relevant. Recently, bonding interpretations based on analyses of the physically observable electronic density have gained popularity and, in this Feature Article, the utility of such density-based approaches is demonstrated. Application of Bader's Quantum Theory of Atoms in Molecules (QTAIM) is shown to elucidate many properties including bonding trends, orbital overlap and energy degeneracy-driven covalency, oxidation state identification and bond stability, demonstrating the increasingly important role that simulation and analysis play in the area of f-element bond characterisation.

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Section: Oxidation State Identificationmentioning

confidence: 99%

Quantification of f-element covalency through analysis of the electron density: insights from simulation

2017

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“…Simulations were performed using both wavefunction-and density-based methodologies: complete/restricted active space self-consistent field (CASSCF/RASSCF) theory and density functional theory (DFT). In order to investigate the effects of including exact exchange, DFT calculations compared the GGA PBE [37] and hybrid-GGA B3LYP [38,39] exchange-correlation functionals: our group has successfully employed B3LYP in previous studies of actinide complexes [4,[40][41][42], while the application of multiconfigurational approaches to the study of actinide complexes is well established: see [43] for a recent example.…”

Section: Computational Detailsmentioning

confidence: 99%

Assessing Covalency in Cerium and Uranium Hexachlorides: A Correlated Wavefunction and Density Functional Theory Study

Beekmeyer

Kerridge

2015

Inorganics

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The electronic structure of a series of uranium and cerium hexachlorides in a variety of oxidation states was evaluated at both the correlated wavefunction and density functional (DFT) levels of theory. Following recent experimental observations of covalency in tetravalent cerium hexachlorides, bonding character was studied using topological and integrated analysis based on the quantum theory of atoms in molecules (QTAIM). This analysis revealed that M-Cl covalency was strongly dependent on oxidation state, with greater covalency found in higher oxidation state complexes. Comparison of M-Cl delocalisation indices revealed a discrepancy between correlated wavefunction and DFT-derived values. Decomposition of these delocalisation indices demonstrated that the origin of this discrepancy lay in ungerade contributions associated with the f-manifold which we suggest is due to self-interaction error inherent to DFT-based methods. By all measures used in this study, extremely similar levels of covalency between complexes of U and Ce in the same oxidation state was found.

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“…Many aspects of these studies challenge the traditional viewpoints that the 4f electrons are entirely localized on the lanthanide and that bonding with the oxide ligands is best described using electrostatic models. Qualitatively, invoking a degree of covalent Ln-O bonding in LnO 2 could be justified given the growing number of synthetic, [38][39][40][41][42][43][44][45][46] magnetic, [47][48][49][50][51][52][53] spectroscopic, [54][55][56][57][58][59][60] and theoretical 30,[61][62][63][64][65][66][67] studies indicating that strictly ionic models of lanthanide bonding are inadequate. For example, a new class of compounds has emerged containing lanthanide and other rare earth metals bound to oxo, 38,[68][69] imido, [70][71][72][73] and carbene ligands, [74][75][76][77] among others.…”

Section: Introductionmentioning

confidence: 99%

Quantitative Evidence for Lanthanide-Oxygen Orbital Mixing in CeO₂, PrO₂, and TbO₂

et al. 2017

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Understanding the nature of covalent (band-like) vs ionic (atomic-like) electrons in metal oxides continues to be at the forefront of research in the physical sciences. In particular, the development of a coherent and quantitative model of bonding and electronic structure for the lanthanide dioxides, LnO (Ln = Ce, Pr, and Tb), has remained a considerable challenge for both experiment and theory. Herein, relative changes in mixing between the O 2p orbitals and the Ln 4f and 5d orbitals in LnO are evaluated quantitatively using O K-edge X-ray absorption spectroscopy (XAS) obtained with a scanning transmission X-ray microscope and density functional theory (DFT) calculations. For each LnO, the results reveal significant amounts of Ln 5d and O 2p mixing in the orbitals of t (σ-bonding) and e (π-bonding) symmetry. The remarkable agreement between experiment and theory also shows that significant mixing with the O 2p orbitals occurs in a band derived from the 4f orbitals of a symmetry (σ-bonding) for each compound. However, a large increase in orbital mixing is observed for PrO that is ascribed to a unique interaction derived from the 4f orbitals of t symmetry (σ- and π-bonding). O K-edge XAS and DFT results are compared with complementary L-edge and M-edge XAS measurements and configuration interaction calculations, which shows that each spectroscopic approach provides evidence for ground state O 2p and Ln 4f orbital mixing despite inducing very different core-hole potentials in the final state.

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All-electron CASPT2 study of Ce(η8–C8H6)2

Cited by 23 publications

References 37 publications

Quantification of f-element covalency through analysis of the electron density: insights from simulation

Quantification of f-element covalency through analysis of the electron density: insights from simulation

Assessing Covalency in Cerium and Uranium Hexachlorides: A Correlated Wavefunction and Density Functional Theory Study

Quantitative Evidence for Lanthanide-Oxygen Orbital Mixing in CeO₂, PrO₂, and TbO₂

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All-electron CASPT2 study of Ce(η8–C8H6)2

Cited by 23 publications

References 37 publications

Quantification of f-element covalency through analysis of the electron density: insights from simulation

Quantification of f-element covalency through analysis of the electron density: insights from simulation

Assessing Covalency in Cerium and Uranium Hexachlorides: A Correlated Wavefunction and Density Functional Theory Study

Quantitative Evidence for Lanthanide-Oxygen Orbital Mixing in CeO2, PrO2, and TbO2

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Quantitative Evidence for Lanthanide-Oxygen Orbital Mixing in CeO₂, PrO₂, and TbO₂