Spin‐State Energetics of Fe<sup>II</sup> Complexes – The Continuing Voyage Through the Density Functional Minefield

Houghton, B. J.; Deeth, Robert J.

doi:10.1002/ejic.201402253

Cited by 42 publications

(31 citation statements)

References 83 publications

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“…That is, more electron-withdrawing pyridine substitutents raise T ½ and stabilize the low-spin states of the complexes. Similar results were obtained in solution for two series of complexes of polydentate ligands, [Fe(Py 4´R tacn)(NCMe) 2 ] 2+ [37,92] and [Fe(stybp R ) 2 ] 2+ [93] (Scheme 7). In both cases, electron-withdrawing substituents on the 4-pyridyl ligand donors were observed to lower the room temperature magnetic moment or to raise T ½ , both consistent with stabilization of the low-spin state.…”

Section: Electronic Influence Of Ligand Substituents On Metal Ion Spisupporting

confidence: 79%

“…Steric bulk at the periphery of the ligand sphere can promote the low-spin state if it inhibits expansion of the metal coordination sphere, or the high-spin state if it leads to distortion of the ligandÑmetal dative interaction. These effects can be reliably understood or predicted in individual compounds computationally [43,50,92] or using molecular models.…”

Section: Discussionmentioning

confidence: 99%

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The Effect of Ligand Design on Metal Ion Spin State—Lessons from Spin Crossover Complexes

2016

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Abstract:The relationship between chemical structure and spin state in a transition metal complex has an important bearing on mechanistic bioinorganic chemistry, catalysis by base metals, and the design of spin crossover materials. The latter provide an ideal testbed for this question, since small changes in spin state energetics can be easily detected from shifts in the spin crossover equilibrium temperature. Published structure-function relationships relating ligand design and spin state from the spin crossover literature give varied results. A sterically crowded ligand sphere favors the expanded metal-ligand bonds associated with the high-spin state. However, steric clashes at the molecular periphery can stabilize either the high-spin or the low-spin state in a predictable way, depending on their effect on ligand conformation. In the absence of steric influences, the picture is less clear since electron-withdrawing ligand substituents are reported to favor the low-spin or the high-spin state in different series of compounds. A recent study has shed light on this conundrum, showing that the electronic influence of a substituent on a coordinated metal ion depends on its position on the ligand framework. Finally, hydrogen bonding to complexes containing peripheral N-H groups consistently stabilizes the low-spin state, where this has been quantified.

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Section: Electronic Influence Of Ligand Substituents On Metal Ion Spisupporting

confidence: 79%

Section: Discussionmentioning

confidence: 99%

The Effect of Ligand Design on Metal Ion Spin State—Lessons from Spin Crossover Complexes

2016

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“…Relative spin-state energies of Fe-complexes is ac hallenge for quantum chemistry,a nd one must tread cautiously through what Deeth has evocatively termeda"density functional minefield". [26] Neese has shownt he same ordering of spin states for Ta uD is obtained with B3LYP as from methods which explicitly account for static correlation (CASSCF,N EVPT2), although oxygen binding is stronger using am ulti-reference approach. [27] We have examined as election of exchange-correlation functionals employing the generalized gradienta pproximation( GGA), including hybrid( B3LYP and B3PW91) and pure (BP86)f unctionals, and the hybrid meta-GGA functional M06 ( Figure 3).…”

Section: Qm Calculationsmentioning

confidence: 73%

Dioxygen Binding in the Active Site of Histone Demethylase JMJD2A and the Role of the Protein Environment

Cortopassi

Simion

Honsby

et al. 2015

Chemistry A European J

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JMJD2A catalyses the demethylation of di- and trimethylated lysine residues in histone tails and is a target for the development of new anticancer medicines. Mechanistic details of demethylation are yet to be elucidated and are important for the understanding of epigenetic processes. We have evaluated the initial step of histone demethylation by JMJD2A and demonstrate the dramatic effect of the protein environment upon oxygen binding using quantum mechanics/molecular mechanics (QM/MM) calculations. The changes in electronic structure have been studied for possible spin states and different conformations of O2 , using a combination of quantum and classical simulations. O2 binding to this histone demethylase is computed to occur preferentially as an end-on superoxo radical bound to a high-spin ferric centre, yielding an overall quintet ground state. The favourability of binding is strongly influenced by the surrounding protein: we have quantified this effect using an energy decomposition scheme into electrostatic and dispersion contributions. His182 and the methylated lysine assist while Glu184 and the oxoglutarate cofactor are deleterious for O2 binding. Charge separation in the superoxo-intermediate benefits from the electrostatic stabilization provided by the surrounding residues, stabilizing the binding process significantly. This work demonstrates the importance of the extended protein environment in oxygen binding, and the role of energy decomposition in understanding the physical origin of binding/recognition.

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“…1). The results, however, are sensitive to the basis set employed and require experimental support if one is to have confidence in the outcome [24][25][26] .…”

Section: Introductionmentioning

confidence: 99%

Combining microscopic and macroscopic probes to untangle the single-ion anisotropy and exchange energies in an S=1 quantum antiferromagnet

et al. 2017

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. (2017) Combining microscopic and macroscopic probes to untangle the single-ion anisotropy and exchange energies in an S=1 quantum antiferromagnet. Physical Review B (Condensed Matter and Materials Physics), 95 (13). 134435. Permanent WRAP URL:http://wrap.warwick.ac.uk/87422 Copyright and reuse:The Warwick Research Archive Portal (WRAP) makes this work by researchers of the University of Warwick available open access under the following conditions. Copyright © and all moral rights to the version of the paper presented here belong to the individual author(s) and/or other copyright owners. To the extent reasonable and practicable the material made available in WRAP has been checked for eligibility before being made available.Copies of full items can be used for personal research or study, educational, or not-for-profit purposes without prior permission or charge. Provided that the authors, title and full bibliographic details are credited, a hyperlink and/or URL is given for the original metadata page and the content is not changed in any way. A note on versions:The version presented in WRAP is the published version or, version of record, and may be cited as it appears here.For more information, please contact the WRAP Team at: wrap@warwick.ac.ukCombining micro-and macroscopic probes to untangle single-ion anisotropy and exchange energies in a S = 1 quantum antiferromagnet The magnetic ground state of the quasi-one-dimensional spin-1 antiferromagnetic chain is sensitive to the relative sizes of the single-ion anisotropy (D) and the intrachain (J) and interchain (J ) exchange interactions. The ratios D/J and J /J dictate the material's placement in one of three competing phases: a Haldane gapped phase, a quantum paramagnet and an XY -ordered state, with a quantum critical point at their junction. We have identified [Ni(HF)2(pyz)2]SbF6, where pyz = pyrazine, as a rare candidate in which this behavior can be explored in detail. Combining neutron scattering (elastic and inelastic) in applied magnetic fields of up to 10 tesla and magnetization measurements in fields of up to 60 tesla with numerical modeling of experimental observables, we are able to obtain accurate values of all of the parameters of the Hamiltonian [D = 13.3(1) K, J = 10.4(3) K and J = 1.4(2) K], despite the polycrystalline nature of the sample. Densityfunctional theory calculations result in similar couplings (J = 9.2 K, J = 1.8 K) and predict that the majority of the total spin population resides on the Ni(II) ion, while the remaining spin density is delocalized over both ligand types. The general procedures outlined in this paper permit phase boundaries and quantum-critical points to be explored in anisotropic systems for which single crystals are as yet unavailable.

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Spin‐State Energetics of Fe^II Complexes – The Continuing Voyage Through the Density Functional Minefield

Cited by 42 publications

References 83 publications

The Effect of Ligand Design on Metal Ion Spin State—Lessons from Spin Crossover Complexes

The Effect of Ligand Design on Metal Ion Spin State—Lessons from Spin Crossover Complexes

Dioxygen Binding in the Active Site of Histone Demethylase JMJD2A and the Role of the Protein Environment

Combining microscopic and macroscopic probes to untangle the single-ion anisotropy and exchange energies in an S=1 quantum antiferromagnet

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Spin‐State Energetics of FeII Complexes – The Continuing Voyage Through the Density Functional Minefield

Cited by 42 publications

References 83 publications

The Effect of Ligand Design on Metal Ion Spin State—Lessons from Spin Crossover Complexes

The Effect of Ligand Design on Metal Ion Spin State—Lessons from Spin Crossover Complexes

Dioxygen Binding in the Active Site of Histone Demethylase JMJD2A and the Role of the Protein Environment

Combining microscopic and macroscopic probes to untangle the single-ion anisotropy and exchange energies in an S=1 quantum antiferromagnet

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Product

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Spin‐State Energetics of Fe^II Complexes – The Continuing Voyage Through the Density Functional Minefield