Experimental Charge Densities from Multipole Modeling: Moving into the Twenty-First Century

Damgaard‐Møller, Emil; Krause, Lennard; Overgaard, Jacob

doi:10.1007/430_2020_61

Cited by 3 publications

(4 citation statements)

References 92 publications

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“…The ED was modeled using XD2016, which is based on the Hansen–Coppens multipole formalism, in which the atomic density for each atom is expanded into three terms: an unperturbed spherical core, a spherical valence term that allows refinement of valence population parameters and, thus, electron transfer between atoms, and finally an aspherical term that includes a set of refinable multipole population parameters that redistribute the spherically organized valence electrons of a given atom using spherical harmonic angular functions . We have recently reviewed the use of the ED approach in molecular magnetism . The multipole model uses a local coordinate system defined as z : Co–S(4) and x : Co–S(2).…”

Section: Experimental Methodsmentioning

confidence: 99%

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Investigating Complex Magnetic Anisotropy in a Co(II) Molecular Compound: A Charge Density and Correlated Ab Initio Electronic Structure Study

et al. 2020

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Section: Experimental Methodsmentioning

confidence: 99%

“…39 We have recently reviewed the use of the ED approach in molecular magnetism. 40 The multipole model uses a local coordinate system defined as z: Co-S(4) and x: Co-S(2). All C-H distances were fixed at mean bond length values obtained from tabulated neutron diffraction data.…”

Section: Synthesis Of [Co(bm Me )2]mentioning

confidence: 99%

Investigating Complex Magnetic Anisotropy in a Co(II) Molecular Compound: A Charge Density and Correlated Ab Initio Electronic Structure Study

et al. 2020

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“…The radial functions, R l ( κ ′ r ), are nodeless, single-zeta Slater functions with optimized coefficients and exponents. The functions denoted d lm ± are angular orbital-like functions . To enhance aspherical features, we used the Laplacian of the electron density.…”

Section: Methodsmentioning

confidence: 99%

“…The functions denoted d lm± are angular orbital-like functions. 38 To enhance aspherical features, we used the Laplacian of the electron density. The negative of the Laplacian will have maxima in regions of accumulated density and minima in the regions of charge depletion.…”

Section: ■ Experimental Sectionmentioning

confidence: 99%

Electron Density Analysis of Metal–Metal Bonding in a Ni₄Cluster Featuring Ferromagnetic Exchange

et al. 2022

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We present a combined experimental and theoretical study of the nature of the proposed metal−metal bonding in the tetranuclear cluster Ni 4 (NP t Bu 3 ) 4 , which features four nickel(I) centers engaged in strong ferromagnetic coupling. High-resolution single-crystal synchrotron X-ray diffraction data collected at 25 K provide an accurate geometrical structure and a multipole model electron density description. Topological analysis of the electron density in the Ni 4 N 4 core using the quantum theory of atoms in molecules clearly identifies the bonding as an eight-membered ring of type [Ni−N−] 4 without direct Ni−Ni bonding, and this result is generally corroborated by an analysis of the energy density distribution. In contrast, the calculated bond delocalization index of ∼0.6 between neighboring Ni atoms is larger than what has been found for other bridged metal−metal bonds and implies direct Ni−Ni bonding. Similar support for the presence of direct Ni−Ni bonding is found in the interacting quantum atom approach, an energy decomposition scheme, which suggests the presence of stabilizing Ni−Ni bonding interactions with an exchange-correlation energy contribution approximately 50% of that of the Ni−N interactions. Altogether, while the direct interactions between neighboring Ni centers are too weak and sterically constrained to bear the signature of a topological bond critical point, other continuous measures clearly indicate significant Ni−Ni bonding. These metal−metal bonding interactions likely mediate direct ferromagnetic exchange, giving rise to the high-spin ground state of the molecule.

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Quantifying magnetic anisotropy using X-ray and neutron diffraction

Klahn¹,

Damgaard‐Møller²,

Krause³

et al. 2021

IUCrJ

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In this work, the magnetic anisotropy in two iso-structural distorted tetrahedral Co(II) complexes, CoX 2tmtu2 [X = Cl(1) and Br(2), tmtu = tetramethylthiourea] is investigated, using a combination of polarized neutron diffraction (PND), very low-temperature high-resolution synchrotron X-ray diffraction and CASSCF/NEVPT2 ab initio calculations. Here, it was found consistently among all methods that the compounds have an easy axis of magnetization pointing nearly along the bisector of the compression angle, with minute deviations between PND and theory. Importantly, this work represents the first derivation of the atomic susceptibility tensor based on powder PND for a single-molecule magnet and the comparison thereof with ab initio calculations and high-resolution X-ray diffraction. Theoretical ab initio ligand field theory (AILFT) analysis finds the d xy orbital to be stabilized relative to the d xz and d yz orbitals, thus providing the intuitive explanation for the presence of a negative zero-field splitting parameter, D, from coupling and thus mixing of d xy and d x 2 − y 2 . Experimental d-orbital populations support this interpretation, showing in addition that the metal–ligand covalency is larger for Br-ligated 2 than for Cl-ligated 1.

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Experimental Charge Densities from Multipole Modeling: Moving into the Twenty-First Century

Cited by 3 publications

References 92 publications

Investigating Complex Magnetic Anisotropy in a Co(II) Molecular Compound: A Charge Density and Correlated Ab Initio Electronic Structure Study

Investigating Complex Magnetic Anisotropy in a Co(II) Molecular Compound: A Charge Density and Correlated Ab Initio Electronic Structure Study

Electron Density Analysis of Metal–Metal Bonding in a Ni₄Cluster Featuring Ferromagnetic Exchange

Quantifying magnetic anisotropy using X-ray and neutron diffraction

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Experimental Charge Densities from Multipole Modeling: Moving into the Twenty-First Century

Cited by 3 publications

References 92 publications

Investigating Complex Magnetic Anisotropy in a Co(II) Molecular Compound: A Charge Density and Correlated Ab Initio Electronic Structure Study

Investigating Complex Magnetic Anisotropy in a Co(II) Molecular Compound: A Charge Density and Correlated Ab Initio Electronic Structure Study

Electron Density Analysis of Metal–Metal Bonding in a Ni4Cluster Featuring Ferromagnetic Exchange

Quantifying magnetic anisotropy using X-ray and neutron diffraction

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Electron Density Analysis of Metal–Metal Bonding in a Ni₄Cluster Featuring Ferromagnetic Exchange