Relativistic quantum chemical calculations show that the uranium molecule U2 has a quadruple bond

Knecht, Stefan; Jensen, Hans Jørgen Aa.; Saue, Trond

doi:10.1038/s41557-018-0158-9

Cited by 84 publications

(101 citation statements)

References 49 publications

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“…Nevertheless, the inclusion of the spin-orbit coupling (SOC) in the computation of EBOs is quite straightforward and has been first reported by Gendron et al [12] and independently reported soon after by some of us [13]. Furthermore, the EBO concept has also been very recently generalized to the fully relativistic frameworks [14], and thus we consider that it should now be admitted that the SOC must not be neglected while computing EBOs in heavy-element systems.…”

Section: Introductionmentioning

confidence: 86%

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Relevance of effective bond orders in heterodiatomic molecules and role of the spin-orbit coupling in theAtX(X=At–F)series

et al. 2019

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Scalar and spin-dependent relativistic effects can influence the geometries and wave functions of the ground and excited states of molecular systems in a way that is not always trivial. However, it is still common for researchers, in particular within the quantum chemistry community, to neglect the spin-dependent effects while discussing the binding between atoms in heavy-element systems. Within multiconfigurational self-consistent field frameworks, the binding in diatomic molecules can be derived from the occupation of the natural orbitals, which by definition form a basis that diagonalizes the one-body density matrix. This does not fully prevent arbitrariness, and the first objective of the present paper will be to review the concept of effective bond order, in particular with respect to the rounding up rule. Then, the respective roles of the scalar and the spin-dependent relativistic effects on the bond lengths are investigated by means of state-of-the-art nonrelativistic, scalarrelativistic, and exact two-component coupled-cluster calculations, providing reference molecular geometries for the whole AtX (X = At-F) series. A diagnostic of relevance for defining effective bond orders in heterodiatomic molecules is introduced and applied to this series, showing that the more dissymmetric the system, the less defined the effective bond order is. Finally, the role of the spin-orbit coupling on the effective bond orders is discussed. AtI appears as a key intermediate in the series in terms of the ground-state π bonding or antibonding character. Although emphasis will be put on ground states, the present methodology is readily applicable to the description of excited states.

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Section: Introductionmentioning

confidence: 86%

“…and bonding or antibonding characters, even in homodiatomic molecules. Because of this, Knecht et al proposed to define a generalized EBO (gEBO) as follows [14]:…”

Section: Relativistic Effective Bond Orders: Spin-orbit Coupling Amentioning

confidence: 99%

Relevance of effective bond orders in heterodiatomic molecules and role of the spin-orbit coupling in theAtX(X=At–F)series

et al. 2019

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“…Of particulari nterest are covalent interactions involving fa tomico rbitals. [2][3][4][5][6][7][8][9] Compared to d-block elements, [10,11] the chemical bonding in compounds with f-block elements, especially with actinides (An, 5f), is much less understood. Therefore, An-ligand bonding is currently of very high interesti nb oth the theoretical and experimental chemistry communities.…”

Section: Introductionmentioning

confidence: 99%

Ab Initio Analysis of Metal–Ligand Bonding in An(COT)₂ with An=Th, U in Their Ground‐ and Core‐Excited States

Ganguly

Sergentu

Autschbach

2020

Chemistry A European J

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Relativistic multireference ab initio wave function calculations with the restricted active space second-order perturbation theory (RASPT2) were performed on thorocene and uranocene to determine the actinide N 4,5 -edge and carbon K-edge X-ray absorption near-edge structure (XANES) intensities andt he metal-ligand orbitalm ixingi nt he ground state and core-excited states. Calculated spectrali ntensities show very good agreement with the experiments and therefore allow detailed and unambiguous assignment of the observed spectral features. f-type covalent bonding or antibonding interactions are observed for thorocene in the core-excited states, thoughn ot in the ground state. This is because the molecular orbital of f symmetry,w hich is the in-phasec ombination of the ligand L f and the Th 5f f orbitals, can be populated with electrons in core-excited states, whereas it is essentially unoccupied in the ground state. For uranocene, the XANES spectra do not reveal much information beyondm ultipletb roadening, despite the presence of distinct peaks in the spectra. Every core-excited peak is best characterized by its own set of bond orbitals, as the excited state covalency is clearly different from the ground state covalency.[a] Dr.

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“…[30,31] Second,a sp reviously mentioned, the advent of new theoretical approaches to calculate the electronic structure of heavy element compounds became much less costly. [32] Third, as eminalw ork by Prodan et al showeda nu nexpected component of actinide-ligand bonds in which degeneracy occurs between oxygen or nitrogen 2p ligand orbitals and leads to substantial entanglement of metal and ligand orbitals even when overlap is minimal. [33,34] Fourth,i tb ecame recognized as the result of these computational advances that an array of frontier orbitals are availablef or bonding.…”

Section: Introductionmentioning

confidence: 99%

Contemporary Chemistry of Berkelium and Californium

White

Dan

Albrecht‐Schönzart

2019

Chemistry A European J

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The merging of small‐scale syntheses and rapid crystallization methods have provided access to crystalline samples of berkelium (Z=97) and californium (Z=98) coordination complexes and compounds that can be interrogated with a suite of spectroscopic tools and structural elucidation approaches that have come online over the last 20 years. The combination of this experimental data with relativistic theoretical methods that capture the effects of spin‐orbit coupling and scalar relativistic effects have allowed us to understand the electronic structure of berkelium and californium compounds at a level of detail that was not previously possible. The harbinger of this new era of post‐curium chemistry was the synthesis and characterization of [Cf{B6O8(OH)5}]. This compound possesses a structure type that is distinct from earlier actinide borates, a reduction in coordination number for californium, contracted Cf−O bond lengths, a substantially reduced magnetic moment with respect to the calculated free‐ion moment and, most importantly, vibronically coupled broadband photoluminescence. Ligand‐field analysis also showed that the splitting of the ground state was larger than typically found in the f‐block elements, and when taken together places its overall electronic structure as a hybrid of d‐ and f‐block components. The discovery of the unusual properties of this compound has led to the development of large families of 4f and 5f coordination complexes, in an effort to uncover the underlying origin of the electronic structure oddities, and whether there really is a sharp onset of these changes at californium. This in turn pushed the development of far more challenging berkelium chemistry (from a radiologic standpoint) because the half‐life of the isotopes decreases from 351 years for 249Cf to 330 days for 249Bk. This short review details some of the chemistry that has been reported over the last 15 years, and its consequences for understanding the periodic table.

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Relativistic quantum chemical calculations show that the uranium molecule U2 has a quadruple bond

Cited by 84 publications

References 49 publications

Relevance of effective bond orders in heterodiatomic molecules and role of the spin-orbit coupling in theAtX(X=At–F)series

Relevance of effective bond orders in heterodiatomic molecules and role of the spin-orbit coupling in theAtX(X=At–F)series

Ab Initio Analysis of Metal–Ligand Bonding in An(COT)₂ with An=Th, U in Their Ground‐ and Core‐Excited States

Contemporary Chemistry of Berkelium and Californium

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Relativistic quantum chemical calculations show that the uranium molecule U2 has a quadruple bond

Cited by 84 publications

References 49 publications

Relevance of effective bond orders in heterodiatomic molecules and role of the spin-orbit coupling in theAtX(X=At–F)series

Relevance of effective bond orders in heterodiatomic molecules and role of the spin-orbit coupling in theAtX(X=At–F)series

Ab Initio Analysis of Metal–Ligand Bonding in An(COT)2 with An=Th, U in Their Ground‐ and Core‐Excited States

Contemporary Chemistry of Berkelium and Californium

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Ab Initio Analysis of Metal–Ligand Bonding in An(COT)₂ with An=Th, U in Their Ground‐ and Core‐Excited States