Temperature and Counterion Dependent Spin Crossover in a Hexaamineiron(II) Complex

Connolly, Blake J. P.; Brosius, Victor; Mertes, Nicole; Demidova, Caroline; Bilyj, Jessica K.; Riley, Mark J.; Bernhardt, Paul V.

doi:10.1002/ejic.202100560

Cited by 3 publications

(1 citation statement)

References 92 publications

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“…The SCO behavior of a complex is influenced by its ligands, 60 crystal packing effects, 30,[61][62][63] and intermolecular interactions. [64][65][66][67] While a combination of experimental techniques can characterize SCO behavior through measurement of structural changes and T1/2, it is challenging to rationalize experimental trends to determine how T1/2 can be varied for use in molecular devices. 35 Empirical models proposed for predicting SCO behavior, e.g., based on N-N distances in tris-homoleptic bidentate ligands of Fe(II) complexes 68 , often lack transferability (e.g., to other denticities).…”

Section: Introductionmentioning

confidence: 99%

Assessing the Performance of Approximate Density Functional Theory on 95 Experimentally Characterized Fe(II) Spin Crossover Complexes

Vennelakanti

Taylor

Nandy

et al. 2023

Preprint

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Spin crossover (SCO) complexes, which exhibit changes in spin state in response to external stimuli, have applications in molecular electronics and are challenging materials for computational design. We curate a data set of 95 Fe(II) SCO complexes (SCO-95) from the Cambridge Structural Database that have available low- and high-temperature crystal structures and, in most cases, confirmed experimental spin transition temperatures (T1/2). We study these complexes using density functional theory (DFT) with thirty functionals spanning across multiple rungs of “Jacob’s ladder” to understand the effect of exchange-correlation functional on electronic and Gibbs free energies associated with spin crossover. We specifically assess the effect of varying the Hartree–Fock exchange fraction (aHF) in structures and properties within the B3LYP family of functionals. We identify three best-performing functionals, a modified version of B3LYP (aHF = 0.10), M06-L, and TPSSh, that accurately predict SCO behavior for the majority of the complexes. Contrary to observations from prior studies, double-hybrids with higher aHF values are found to strongly stabilize high-spin states and therefore exhibit poor performance in predicting SCO behavior. Computationally predicted T1/2 values are consistent among the three functionals but show limited correlation to experimentally reported T1/2 values. These failures are attributed to the lack of crystal packing effects and counter-anions in the DFT calculations that would be needed to account for phenomena like hysteresis and two-step SCO behavior. The SCO-95 set thus presents opportunities for method development, both in terms of increasing model complexity and method fidelity.

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Section: Introductionmentioning

confidence: 99%

Assessing the Performance of Approximate Density Functional Theory on 95 Experimentally Characterized Fe(II) Spin Crossover Complexes

Vennelakanti

Taylor

Nandy

et al. 2023

Preprint

View full text Add to dashboard Cite

show abstract

Theoretical approach to the one-step versus two-step spin transitions in Hofmann-like FeII SCO metal-organic frameworks

Arias-Olivares

Sánchez-de-Armas

Calzado

2023

Materials Today Chemistry

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Assessing the performance of approximate density functional theory on 95 experimentally characterized Fe(II) spin crossover complexes

Vennelakanti

Taylor

Nandy

et al. 2023

The Journal of Chemical Physics

View full text Add to dashboard Cite

Spin crossover (SCO) complexes, which exhibit changes in spin state in response to external stimuli, have applications in molecular electronics and are challenging materials for computational design. We curate a dataset of 95 Fe(II) SCO complexes (SCO-95) from the Cambridge Structural Database that have available low- and high-temperature crystal structures and, in most cases, confirmed experimental spin transition temperatures (T1/2). We study these complexes using density functional theory (DFT) with 30 functionals spanning across multiple rungs of “Jacob’s ladder” to understand the effect of exchange–correlation functional on electronic and Gibbs free energies associated with spin crossover. We specifically assess the effect of varying the Hartree–Fock exchange fraction (aHF) in structures and properties within the B3LYP family of functionals. We identify three best-performing functionals, a modified version of B3LYP (aHF = 0.10), M06-L, and TPSSh, that accurately predict SCO behavior for the majority of the complexes. While M06-L performs well, MN15-L, a more recently developed Minnesota functional, fails to predict SCO behavior for all complexes, which could be the result of differences in datasets used for parametrization of M06-L and MN15-L and also the increased number of parameters for MN15-L. Contrary to observations from prior studies, double-hybrids with higher aHF values are found to strongly stabilize high-spin states and therefore exhibit poor performance in predicting SCO behavior. Computationally predicted T1/2 values are consistent among the three functionals but show limited correlation to experimentally reported T1/2 values. These failures are attributed to the lack of crystal packing effects and counter-anions in the DFT calculations that would be needed to account for phenomena such as hysteresis and two-step SCO behavior. The SCO-95 set thus presents opportunities for method development, both in terms of increasing model complexity and method fidelity.

show abstract

Temperature and Counterion Dependent Spin Crossover in a Hexaamineiron(II) Complex

Cited by 3 publications

References 92 publications

Assessing the Performance of Approximate Density Functional Theory on 95 Experimentally Characterized Fe(II) Spin Crossover Complexes

Assessing the Performance of Approximate Density Functional Theory on 95 Experimentally Characterized Fe(II) Spin Crossover Complexes

Theoretical approach to the one-step versus two-step spin transitions in Hofmann-like FeII SCO metal-organic frameworks

Assessing the performance of approximate density functional theory on 95 experimentally characterized Fe(II) spin crossover complexes

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