Accurate Magnetic Couplings in Chromium-Based Molecular Rings from Broken-Symmetry Calculations within Density Functional Theory

Weissman, Shira; Antkowiak, Michał; Brzostowski, B.; Kamieniarz, G.; Kronik, Leeor

doi:10.1021/acs.jctc.9b00459

Cited by 10 publications

(8 citation statements)

References 86 publications

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“…For example, for Cr 8 ring, the exchange constant Γ " 1.65meV appeared to be substantially lower than 3.5meV obtained from previous DFT calculations. However, this value is still clearly greater than predicted from the experiments Γ " 1.46meV , and also greater than that obtained from the new DFT calculations reported in [16].…”

Section: Introductioncontrasting

confidence: 66%

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Description of molecular nanomagnets by the multi-orbital Hubbard model with correlated hopping

Matysiak,

Lemański

2021

Preprint

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We present a microscopic description of molecular magnets by the multi-orbital Hubbard model, which includes the correlated hopping term, i.e. the dependence of electron hopping amplitude between orbitals on the degree of their occupancy. In the limit of large Coulomb on-site interaction, we derived the spin Hamiltonian using the perturbation theory. The magnetic coupling constant between two ions we determined in two different ways: a)from the expression obtained in the perturbation calculus and b)from the analysis of distances between the lowest levels of the energy spectrum obtained by the diagonalization of the multi-orbital Hubbard model. The procedure we use can be applied to various nanomagnets, but the final calculations we performed for the molecular ring Cr8. We showed that the correlated hopping can reduce the antiferromagnetic exchange between ions, what is essential for a proper description of Cr8.

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Section: Introductioncontrasting

confidence: 66%

“…ferromagnetic and antiferromagnetic of the Neel's type) do not lead to the correct results. Although quite recently it was reported that the magnetic couplings calculated using the symmetry-broken version of DFT are close to those deduced from the experimental data [16].…”

Section: Introductionsupporting

confidence: 57%

Description of molecular nanomagnets by the multi-orbital Hubbard model with correlated hopping

Matysiak,

Lemański

2021

Preprint

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“…DFT is well-known to overestimate J coupling values owing to systematic over-localization of electrons in the DFT method. [69][70][71] Evaluation using both the PBE-sol and LDA functionals as well as with the DFT+U level of theory all provide values that agree within 1 meV per atom. We also used DFT with magnetic supercells to calculate the interchain coupling, JI (Fig.…”

Section: Electronic Structure and Dft Calculationsmentioning

confidence: 81%

The Structure and Magnetic Properties of a New Family of 1D Chromium Thiolate Coordination Polymers

Ritchhart

Filatov

Jeon

et al. 2022

Preprint

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The synthesis, structure, and magnetic properties of two novel, pseudo-1D chromium thiolate coordination polymers (CPs), CrBTT and Cr2BDT3, are reported. The structures of these materials were determined using X-ray powder diffraction revealing highly symmetric 1D chains embedded within a CP framework. The magnetic coupling of this chain system was measured by SQUID magnetometry, revealing a switch from antiferromagnetic to ferromagnetic behavior dictated by the angular geometrical constraints within the CP scaffold consistent with the Goodenough-Kanamori-Anderson rules. Intrachain magnetic coupling constants JNN of −32 K and +5.7 K were found for CrBTT and Cr2BDT3 respectively using the 1D Bonner-Fisher model of magnetism. The band structure of these materials has also been examined by optical spectroscopy and Density Functional Theory (DFT) calculations revealing semiconducting behavior. Our findings here demonstrate how CP scaffolds can support idealized low-dimensional structural motifs and dictate magnetic interactions through tuning of geometry and inter-spin couplings.

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“…The larger values for 3 (−6, −55, −281 cm –1 for [HS–HS], [LS–HS] and [LS–LS], respectively) contrast to the more similar values for 1 (−1, −2, −12 cm –1 for [HS–HS], [LS–HS], and [LS–LS], respectively) and 2 (−2, 0, −11 cm –1 for [HS–HS], [LS–HS], and [LS–LS], respectively) and are consistent with stronger electronic communication mediated by thea 4– compared to weaker communication for spiro 4– and Br 4 spiro 4– . It should be noted that while the signs and relative ordering of these calculated coupling constants are likely reliable, the accuracy of the absolute values is uncertain. − …”

Section: Results and Discussionmentioning

confidence: 99%

Controlling Spin Crossover in a Family of Dinuclear Fe(III) Complexes via the Bis(catecholate) Bridging Ligand

Janetzki,

Chegerev,

Gransbury

et al. 2023

Inorg. Chem.

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Spin crossover (SCO) complexes can reversibly switch between low spin (LS) and high spin (HS) states, affording possible applications in sensing, displays, and molecular electronics. Dinuclear SCO complexes with access to [LS−LS], [LS−HS], and [HS−HS] states may offer increased levels of functionality. The nature of the SCO interconversion in dinuclear complexes is influenced by the local electronic environment. We report the synthesis and characterization of [{Fe III (tpa)} 2 spiro]-(PF 6 ) 2 (1), [{Fe I I I (tpa)} 2 Br 4 spiro](PF 6 ) 2 (2), and [{Fe III (tpa)} 2 thea](PF 6 ) 2 (3) (tpa = tris(2-pyridylmethyl)amine, spiroH 4 = 3,3,3′,3′-tetramethyl-1,1′-spirobi(indan)-5,5′,6,6′-tetraol, Br 4 spiroH 4 = 3,3,3′,3′-tetramethyl-1,1′-spirobi(indan)-4,4′,7,7′-tetrabromo-5,5′,6,6′-tetraol, theaH 4 = 2,3,6,7-tetrahydroxy-9,10-dimethyl-9,10-dihydro-9,10-ethanoanthracene), utilizing non-conjugated bis(catecholate) bridging ligands. In the solid state, magnetic and structural analysis shows that 1 remains in the [HS−HS] state, while 2 and 3 undergo a partial SCO interconversion upon cooling from room temperature involving the mixed [LS−HS] state. In solution, all complexes undergo SCO from [HS−HS] at room temperature, via [LS−HS] to mixtures including [LS−LS] at 77 K, with the extent of SCO increasing in the order 1 < 2 < 3. Gas phase density functional theory calculations suggest a [LS−LS] ground state for all complexes, with the [LS− HS] and [HS−HS] states successively destabilized. The relative energy separations indicate that ligand field strength increases following spiro 4− < Br 4 spiro 4− < thea 4− , consistent with solid-state magnetic and EPR behavior. All three complexes show stabilization of the [LS−HS] state in relation to the midpoint energy between [LS−LS] and [HS−HS]. The relative stability of the [LS−HS] state increases with increasing ligand field strength of the bis(catecholate) bridging ligand in the order 1 < 2 < 3. The bromo substituents of Br 4 spiro 4− increase the ligand field strength relative to spiro 4− , while the stronger ligand field provided by thea 4− arises from extension of the overlapping π-orbital system across the two catecholate units. This study highlights how SCO behavior in dinuclear complexes can be modulated by the bridging ligand, providing useful insights for the design of molecules that can be interconverted between more than two states.

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Accurate Magnetic Couplings in Chromium-Based Molecular Rings from Broken-Symmetry Calculations within Density Functional Theory

Cited by 10 publications

References 86 publications

Description of molecular nanomagnets by the multi-orbital Hubbard model with correlated hopping

Description of molecular nanomagnets by the multi-orbital Hubbard model with correlated hopping

The Structure and Magnetic Properties of a New Family of 1D Chromium Thiolate Coordination Polymers

Controlling Spin Crossover in a Family of Dinuclear Fe(III) Complexes via the Bis(catecholate) Bridging Ligand

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