Magnetic Coupling Constants of Self‐Assembled Cu<sup>II</sup> [3×3] Grids: Alternative Spin Model from Theoretical Calculations

Calzado, Carmen J.; Amor, Nadia Ben; Maynau, Daniel

doi:10.1002/chem.201402224

Cited by 7 publications

(5 citation statements)

References 70 publications

(108 reference statements)

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“…However, both sets of parameters (those previously reported and our calculated values) give fittings of the χ( T ) curve of similar quality. Our result puts in evidence the arbitrariness of the fittings based solely on their quality or accuracy, − arbitrariness particularly significant in the case of AF–F and AF–AF spin models, which are not very sensitive to the individual magnetic coupling values nor to the alternation α = | J inter / J intra | parameter. Thus, this study highlights the relevance of the theoretical calculations as a complementary tool for the understanding of the molecular aspects of magnetism.…”

Section: Discussionmentioning

confidence: 80%

Evaluation of the Magnetic Interactions in Salts Containing [Ni(dmit)₂]⁻ Radical Anions

2017

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This paper reports on a theoretical analysis of the electronic structure and magnetic properties of the [Ni(dmit)2] -radical anions in four salt compounds resulting from the combination with supramolecular cation-crown ether assemblies. The selected compounds are representative examples of the diversity of stacking patterns and magnetic behaviors found for systems based on these [Ni(dmit)2] -anions. Difference Dedicated Configuration Interaction calculations have been performed on fragments containing two neighbor [Ni(dmit)2] -units to evaluate the intradimer, interdimer, and interchain magnetic coupling constants and analyze the electronic structure of the [Ni(dmit)2] -ions. The amplitude and sign of these through-space interactions are consistent with the structure and arrangement of the [Ni(dmit)2] monomers in the chain and the overlap and transfer integral between the magnetic orbitals. They accurately simulate the thermal dependence of the magnetic susceptibility but do not agree with the reported J values in two of the systems, both composed by chains of weak dimers. These results highlight the nonunivocal nature of the fitting in complex systems and the difficulties in defining interaction spin models solely based on the quality of the resulting curves. This work shows the limitations of the extended Hückel calculations on the interpretation of the main ingredients of the magnetism and the relevance of reference theoretical calculations as a complementary tool for the understanding of the magnetic behavior of [Ni(dmit)2]-based functional materials.

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Section: Discussionmentioning

confidence: 80%

Evaluation of the Magnetic Interactions in Salts Containing [Ni(dmit)₂]⁻ Radical Anions

2017

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“…The thresholds used in this work have been previously tested in other systems and are enough to ensure that the relevant excitations are taken into account. Details of this method and recent applications can be found in refs and − , respectively.…”

Section: Methodsmentioning

confidence: 99%

Evaluation of the Giant Ferromagnetic π–d Interaction in Iron-Phthalocyanine Molecule

Sánchez-de-Armas

Calzado

2018

J. Phys. Chem. A

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The interaction between itinerant π and localized d electrons in metal-phthalocyanines, namely, J interaction, is considered as responsible for the giant negative magnetoresistance observed in several phthalocyanine-based conductors, among many other important physical properties. Despite the fundamental and technological importance of this on-site intramolecular interaction, its giant ferromagnetic nature has been only recently demonstrated by the experiments conducted by Murakawa et al. in the neutral radical [Fe(Pc)(CN)]·2CHCl ( Phys. Rev. B 2015 , 92 , 054429 ). In this article, we present the theoretical evaluation of this interaction combining wave function-based electronic calculations on isolated Fe(Pc)(CN) molecules and density functional theory-based periodic calculations on the crystal. Our calculations confirm the ferromagnetic nature of the π-d interaction, with a coupling constant as large as J/k = 570 K, in excellent agreement with the experiments, and the presence of intermolecular antiferromagnetic interactions driven by the π-π overlap of neighboring phthalocyaninato molecules. The analysis of the wave function of the ground state of the Fe(Pc)(CN) molecule provides the clues of the origin of this giant ferromagnetic π-d interaction.

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“…In all the models, the energy of the magnetic states involved in the coupling is evaluated by means of Difference Dedicated Configuration Interaction (DDCI) calculations, combined with the EXSCI approach to make feasible the calculations on the more extended models (see the SI file for a more detailed description). Details of the EXSCI approach and recent applications can be found in refs and − , respectively.…”

Section: Description Of the Models And Computational Detailsmentioning

confidence: 99%

Electronic Structure and Magnetic Interactions in the Radical Salt [BEDT-TTF]₂[CuCl₄]

et al. 2018

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The magnetic behavior and electric properties of the hybrid radical salt [BEDT-TTF][CuCl] have been revisited through extended experimental analyses and DDCI and periodic DFT plane waves calculations. Single crystal X-ray diffraction data have been collected at different temperatures, discovering a phase transition occurring in the 250-300 K range. The calculations indicate the presence of intradimer, interdimer, and organic-inorganic π-d interactions in the crystal, a magnetic pattern much more complex than the Bleaney-Bowers model initially assigned to this material. Although this simple model was good enough to reproduce the magnetic susceptibility data, our calculations demonstrate that the actual magnetic structure is significantly more intricate, with alternating antiferromagnetic 1D chains of the organic BEDT-TTF radical, connected through weak antiferromagnetic interactions with the CuCl ions. Combination of experiment and theory allowed us to unambiguously determine and quantify the leading magnetic interactions in the system. The density-of-states curves confirm the semiconductor nature of the system and the dominant organic contribution of the valence and conduction band edges. This general and combined approach appears to be fundamental in order to properly understand the magnetic structure of these complex materials, where experimental data can actually be fitted from a variety of models and parameters.

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Magnetic Coupling Constants of Self‐Assembled Cu^II [3×3] Grids: Alternative Spin Model from Theoretical Calculations

Cited by 7 publications

References 70 publications

Evaluation of the Magnetic Interactions in Salts Containing [Ni(dmit)₂]⁻ Radical Anions

Evaluation of the Magnetic Interactions in Salts Containing [Ni(dmit)₂]⁻ Radical Anions

Evaluation of the Giant Ferromagnetic π–d Interaction in Iron-Phthalocyanine Molecule

Electronic Structure and Magnetic Interactions in the Radical Salt [BEDT-TTF]₂[CuCl₄]

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Magnetic Coupling Constants of Self‐Assembled CuII [3×3] Grids: Alternative Spin Model from Theoretical Calculations

Cited by 7 publications

References 70 publications

Evaluation of the Magnetic Interactions in Salts Containing [Ni(dmit)2]− Radical Anions

Evaluation of the Magnetic Interactions in Salts Containing [Ni(dmit)2]− Radical Anions

Evaluation of the Giant Ferromagnetic π–d Interaction in Iron-Phthalocyanine Molecule

Electronic Structure and Magnetic Interactions in the Radical Salt [BEDT-TTF]2[CuCl4]

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Magnetic Coupling Constants of Self‐Assembled Cu^II [3×3] Grids: Alternative Spin Model from Theoretical Calculations

Evaluation of the Magnetic Interactions in Salts Containing [Ni(dmit)₂]⁻ Radical Anions

Evaluation of the Magnetic Interactions in Salts Containing [Ni(dmit)₂]⁻ Radical Anions

Electronic Structure and Magnetic Interactions in the Radical Salt [BEDT-TTF]₂[CuCl₄]