Structural approach of the features of the spin crossover transition in iron (II) compounds

Guionneau, Philippe; Létard, Jean‐François; Yufit, Dimitrii S.; Chasseau, D.; Bravic, G.; Goeta, Andrés E.; Howard, Judith A. K.; Kahn, Olivier

doi:10.1039/a808075e

Cited by 123 publications

(142 citation statements)

References 17 publications

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“…50 Therefore the two polymorphs have the same average Fe-N bonds in the two HS (high-temperature or photoinduced) and LS states. Differences are observed by looking at the deformation of the Fe-N 6 octahedron, through the angular distortion parameter 39,51 and on the length distortion parameter ζ [see geometry are similar and small in the LS state, the molecular HS state of BIA I appears significantly more distorted than the one of BIA II, both for the HS stable state above 170 K and the photoinduced one at low temperature. These different deformations of the first coordination sphere around the iron atom, also observed through the larger motion of the ligand (see Fig.…”

Section: Detailed Crystallographic Analysis During Thermal and Pmentioning

confidence: 99%

Intermolecular control of thermoswitching and photoswitching phenomena in two spin-crossover polymorphs

et al. 2012

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We discuss here the important role of intermolecular coupling for the thermal-and light-induced molecular state switching in the solid state. Investigations were performed on the two crystalline polymorphs of the spin-crossover [Fe-(PM-BIA) 2 (NCS) 2 ] material. In addition to structural studies at thermal equilibrium, lightinduced phenomena were investigated through photocrystallography, photomagnetic, and dynamical optical measurements. Strong similarities between the thermal-equilibrium and the out-of-equilibrium light-induced transformations are observed in each polymorph: strong cooperative phenomena in one polymorph versus weak cooperative ones in the second polymorph. These different responses of the two crystalline forms of the compound to external perturbations are discussed at the microscopic level in terms of Ising-like model and two-mode description of on-site molecular potentials.

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Section: Detailed Crystallographic Analysis During Thermal and Pmentioning

confidence: 99%

Intermolecular control of thermoswitching and photoswitching phenomena in two spin-crossover polymorphs

et al. 2012

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“…130, 124520 ͑2009͒ ϫ 10 −3 Å 2 in agreement with the values previously determined for similar compounds. 22,23 This fit curve is then the EXAFS spectrum of the reactant structure ͑or reactant model m 0 , hereafter, m denotes the EXAFS spectra͒ m 0 ͑k͒ = 0 ͑k͒. ͑7͒…”

Section: -3mentioning

confidence: 99%

Structural analysis of ultrafast extended x-ray absorption fine structure with subpicometer spatial resolution: Application to spin crossover complexes

Gawełda¹,

Pham²,

Veen³

et al. 2009

The Journal of Chemical Physics

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We present a novel analysis of time-resolved extended x-ray absorption fine structure ͑EXAFS͒ spectra based on the fitting of the experimental transients obtained from optical pump/x-ray probe experiments. We apply it to the analysis of picosecond EXAFS data on aqueous ͓Fe II ͑bpy͒ 3 ͔ 2+ , which undergoes a light induced conversion from its low-spin ͑LS͒ ground state to the short-lived ͑ Ϸ 650 ps͒ excited high-spin ͑HS͒ state. A series of EXAFS spectra were simulated for a collection of possible HS structures from which the ground state fit spectrum was subtracted to generate transient difference absorption ͑TA͒ spectra. These are then compared with the experimental TA spectrum using a least-squares statistical analysis to derive the structural change. This approach reduces the number of required parameters by cancellation in the differences. It also delivers a unique solution for both the fractional population and the extracted excited state structure. We thus obtain a value of the Fe-N bond elongation in the HS state with subpicometer precision ͑0.203Ϯ 0.008 Å͒.

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“…[1,[4][5][6][7][8][9] A wide range of spin crossover has been observed experimentally, for example, gradual complete, two-step transitions, incomplete transitions with a residual high-spin (HS) species at low temperature, and hysteresis loops. [10][11][12][13] Most of the studies of spin crossover have concentrated on iron(ii) compounds. [14,15] Thermal spin crossover in coordination compounds of the form [Fe(alkyltetrazole) 6 ](X) 2 (with X = BF 4 À , ClO 4 À ) were first described by Franke.…”

Section: Introductionmentioning

confidence: 99%

High‐Spin‐ and Low‐Spin‐State Structures of [Fe(chloroethyltetrazole)₆](ClO₄)₂ from Synchrotron Powder Diffraction Data

Dova

Peschar

Sakata

et al. 2006

Chemistry A European J

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The spin-crossover complex [Fe(teec)(6)](ClO(4))(2) (teec = chloroethyltetrazole) exhibits a 50 % incomplete spin crossover in the temperature range 300-30 K. Time-resolved synchrotron powder diffraction experiments have been carried out to elucidate its structural behavior. We report crystal structure models of this material at 300 K (high spin) and 90 K (low spin), as solved from synchrotron powder diffraction data by using Genetic Algorithm and Parallel Tempering techniques and refined with Rietveld refinement. During short synchrotron powder diffraction experiments (five minutes duration) two distinguishable lattices were observed the quantities of which vary with temperature. The implication of this phenomenon, that is interpreted as a structural phase transition associated with the high-to-low spin crossover, and the structural characteristics of the high-spin and low-spin models are discussed in relation to other compounds showing a similar type of spin-crossover behavior.

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Structural approach of the features of the spin crossover transition in iron (II) compounds

Cited by 123 publications

References 17 publications

Intermolecular control of thermoswitching and photoswitching phenomena in two spin-crossover polymorphs

Intermolecular control of thermoswitching and photoswitching phenomena in two spin-crossover polymorphs

Structural analysis of ultrafast extended x-ray absorption fine structure with subpicometer spatial resolution: Application to spin crossover complexes

High‐Spin‐ and Low‐Spin‐State Structures of [Fe(chloroethyltetrazole)₆](ClO₄)₂ from Synchrotron Powder Diffraction Data

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Structural approach of the features of the spin crossover transition in iron (II) compounds

Cited by 123 publications

References 17 publications

Intermolecular control of thermoswitching and photoswitching phenomena in two spin-crossover polymorphs

Intermolecular control of thermoswitching and photoswitching phenomena in two spin-crossover polymorphs

Structural analysis of ultrafast extended x-ray absorption fine structure with subpicometer spatial resolution: Application to spin crossover complexes

High‐Spin‐ and Low‐Spin‐State Structures of [Fe(chloroethyltetrazole)6](ClO4)2 from Synchrotron Powder Diffraction Data

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High‐Spin‐ and Low‐Spin‐State Structures of [Fe(chloroethyltetrazole)₆](ClO₄)₂ from Synchrotron Powder Diffraction Data