Structure and bonding in trimetallic arrays containing a Cr–Cr quadruple bond: A challenge to density functional theory

Arcisauskaite, Vaida; Spivak, Mariano; McGrady, John E.

doi:10.1016/j.ica.2014.08.061

Cited by 18 publications

(20 citation statements)

References 45 publications

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“…In short, the gross features of the potential energy surfaces are consistent with experiment in so much as unsymmetric geometries are relatively favourable for NO 3 − , but nevertheless we are unable to locate a minimum, local or global, away from the lead diagonal. This reinforces the conclusion reached in our previous papers 37,51 that DFT systematically over-stabilizes the symmetric limit relative to the unsymmetric case.…”

Section: Density Functional Theorysupporting

confidence: 91%

A multiconfigurational approach to the electronic structure of trichromium extended metal atom chains

et al. 2017

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Density functional theory, Complete Active Space Self-Consistent Field (CASSCF) and perturbation theory (CASPT2) methodologies have been used to explore the electronic structure of a series of trichromium Extended Metal Atom Chains (EMACS) with different capping ligands. The study is motivated by the very different structural properties of these systems observed in X-ray experiments: the CN-capped example has a symmetric Cr unit while for the NO-capped analogue the same unit has two very different Cr-Cr bond lengths. Density functional theory fails to locate an unsymmetric minimum for any of the systems studied, although the surface corresponding to the asymmetric stretch is very flat. CASPT2, in contrast, does locate an unsymmetric minimum only for the NO-capped system, although again the surface is very flat. We use the Generalized active space (GASSCF) technique and effective Hamiltonian theory to interrogate the multi-configurational wavefunctions of these systems, and show that the increase in the σ-σ* separation as the chain becomes unsymmetric plays a defining role in the stability of the ground state and its expansion in terms of configuration state functions.

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Section: Density Functional Theorysupporting

confidence: 91%

A multiconfigurational approach to the electronic structure of trichromium extended metal atom chains

et al. 2017

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“…Of specific interest to this work are trimetallic HEMACs of the form M A ≣M A −M B in which a quadruply bonded pair of group VI metals is appended to a high‐spin divalent first row transition metal. In these complexes, the M A and M B

d_{z^{2}}

‐orbitals overlap resulting in a 3‐center/3‐electron bond within the complex in which an unpaired electron occupies a 3‐center σ nb ‐orbital as shown in Scheme C …”

Section: Methodsmentioning

confidence: 85%

Extraordinarily Large Ferromagnetic Coupling (J≥150 cm⁻¹) by Electron Delocalization in a Heterometallic Mo≣Mo−Ni Chain Complex

Chipman

Berry

2017

Chemistry A European J

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The new heterometallic chain compounds Mo Ni(dpa) Cl (1) and [Mo Ni(dpa) Cl ]OTf (2) (dpa=2,2'-dipyridylamine) have been prepared and studied by crystallography and magnetic susceptibility, among other methods. Oxidation of 1 to 2 removes an electron from the multiply bonded Mo unit, consistent with the formulation of 2 containing a (Mo ) ⋅⋅⋅(Ni) core. While 1 contains an S=1, pseudo-octahedral Ni ion, 2 has an S=3/2 ground state, in which the two Ni unpaired electrons, one in a localized δ-orbital and one in a heavily delocalized σ -orbital are joined by an unpaired electron in a Mo-Mo δ-orbital. The S=3/2 ground state is persistent to 300 K, evidencing strong ferromagnetic coupling of the Mo and Ni spins with J≥150 cm . This ferromagnetic interaction occurs via delocalization of a σ -electron across all three metal atoms, forcing ferromagnetic alignment of electrons in orthogonal Ni and Mo δ-symmetry orbitals. We anticipate that this new means of coupling spins can be used as a design principle for the preparation of new compounds with high spin ground states.

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“…[23a,41] The theoretical treatment of the structure and bonding by DFT calculations indicates that all of these complexes possess a considerable delocalization of the σ manifold. [43,44] However, the presence of paramagnetic M B ions in the [M A M A M B (dpa) 4 Cl 2 ] series results in the elongation of the Cr-Cr bond by polarizing its σ spin density, which leads to the localization of the remaining π and δ components. [44] Scheme 8.…”

Section: A -M a -M B Hmscsmentioning

confidence: 99%

“…[43,44] However, the presence of paramagnetic M B ions in the [M A M A M B (dpa) 4 Cl 2 ] series results in the elongation of the Cr-Cr bond by polarizing its σ spin density, which leads to the localization of the remaining π and δ components. [44] Scheme 8. The synthetic strategies for the preparation of M A -M A -M B HMSCs reported by Berry.…”

Section: A -M a -M B Hmscsmentioning

confidence: 99%

“…[62] McGrady et al addressed the relationship between the structure and transport phenomena of metal string complexes by analysis of their conduction channels. [27,44,48,[63][64][65][66] With the development of HMSCs, theoretical studies provide directions for the design of molecular rectifiers. Density functional theory calculations suggested that an asymmetric current-voltage response depends strongly on the symmetry of the dominant conduction channel: π channels are more localized and, hence, afford higher rectification ratios.…”

Section: Single-molecular Conductancementioning

confidence: 99%

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From Homonuclear Metal String Complexes to Heteronuclear Metal String Complexes

et al. 2015

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Keywords:Heterometallic complexes / Metal-metal interactions / Mixed-valent compounds / Electronic structure / Singlemolecule conductanceThe study of metal string complexes with 1D transition-metal frameworks began in the early 1990s. As these complexes provide great insights into metal-metal multiple bonds and may have potential applications as molecular wires, this field of research has grown in the past 20 years. As such, the electronic structures of the simplest trinuclear complexes, the supporting ligand systems, and the single-molecular conduc-

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Structure and bonding in trimetallic arrays containing a Cr–Cr quadruple bond: A challenge to density functional theory

Cited by 18 publications

References 45 publications

A multiconfigurational approach to the electronic structure of trichromium extended metal atom chains

A multiconfigurational approach to the electronic structure of trichromium extended metal atom chains

Extraordinarily Large Ferromagnetic Coupling (J≥150 cm⁻¹) by Electron Delocalization in a Heterometallic Mo≣Mo−Ni Chain Complex

From Homonuclear Metal String Complexes to Heteronuclear Metal String Complexes

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Structure and bonding in trimetallic arrays containing a Cr–Cr quadruple bond: A challenge to density functional theory

Cited by 18 publications

References 45 publications

A multiconfigurational approach to the electronic structure of trichromium extended metal atom chains

A multiconfigurational approach to the electronic structure of trichromium extended metal atom chains

Extraordinarily Large Ferromagnetic Coupling (J≥150 cm−1) by Electron Delocalization in a Heterometallic Mo≣Mo−Ni Chain Complex

From Homonuclear Metal String Complexes to Heteronuclear Metal String Complexes

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Extraordinarily Large Ferromagnetic Coupling (J≥150 cm⁻¹) by Electron Delocalization in a Heterometallic Mo≣Mo−Ni Chain Complex