Further studies on the spin cross-over phenomenon in di-isothiocyanatobis(1,10-phenanthroline)iron(<scp>II</scp>)

Ganguli, P.; Gütlich, Philipp; Müller, Erwin W.; Irler, W.

doi:10.1039/dt9810000441

Cited by 50 publications

(26 citation statements)

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“…This is pointed out by discrepancies of the experimental w M T vs. T curves for the samples prepared by different techniques, or measured in different groups. 29,30,35 Mo¨ssbauer spectroscopy confirms the conclusion about incompleteness of the spin transition in some samples at low temperatures. 35 Taking these issues into consideration, we estimated the ''experimental'' G parameters of the SDM of the materials at hand as follows.…”

Section: Data Collectionsupporting

confidence: 74%

Phenomenological model of spin crossover in molecular crystals as derived from atom–atom potentials

Sinitskiy

Tchougréeff

Dronskowski

2011

Phys. Chem. Chem. Phys.

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The method of atom-atom potentials, previously applied to the analysis of pure molecular crystals formed by either low-spin (LS) or high-spin (HS) forms (spin isomers) of Fe(II) coordination compounds (Sinitskiy et al., Phys. Chem. Chem. Phys., 2009, 11, 10983), is used to estimate the lattice enthalpies of mixed crystals containing different fractions of the spin isomers. The crystals under study were formed by LS and HS isomers of Fe(phen)(2)(NCS)(2) (phen = 1,10-phenanthroline), Fe(btz)(2)(NCS)(2) (btz = 5,5',6,6'-tetrahydro-4H,4'H-2,2'-bi-1,3-thiazine), and Fe(bpz)(2)(bipy) (bpz = dihydrobis(1-pyrazolil)borate, and bipy = 2,2'-bipyridine). For the first time the phenomenological parameters Γ pertinent to the Slichter-Drickamer model (SDM) of several materials were independently derived from the microscopic model of the crystals with use of atom-atom potentials of intermolecular interaction. The accuracy of the SDM was checked against the numerical data on the enthalpies of mixed crystals. Fair semiquantitative agreement with the experimental dependence of the HS fraction on temperature was achieved with use of these values. Prediction of trends in Γ values as a function of chemical composition and geometry of the crystals is possible with the proposed approach, which opens a way to rational design of spin crossover materials with desired properties.

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Section: Data Collectionsupporting

confidence: 74%

Phenomenological model of spin crossover in molecular crystals as derived from atom–atom potentials

Sinitskiy

Tchougréeff

Dronskowski

2011

Phys. Chem. Chem. Phys.

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“…As it has been shown previously19, 27 that the spin state behaviour in these compounds is critically dependent on the method of sample preparation, the recommended21, 23, 24, 26 pyridine Soxhlet extraction method was used,9 which yielded a good crop of very small crystals. The same batch of these crystals was used for all the experiments described below.…”

Section: Resultsmentioning

confidence: 99%

Structural Study of the Thermal and Photochemical Spin States in the Spin Crossover Complex [Fe(phen)₂(NCSe)₂]

MacLean

McGrath

O’Connor

et al. 2003

Chemistry A European J

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The first structural data for [Fe(phen)(2)(NCSe)(2)] (obtained using the extraction method of sample preparation) in its high-spin, low-spin and LIESST induced metastable high-spin states have been recorded using synchrotron radiation single crystal diffraction. The space group for all of the spin states was found to be Pbcn. On cooling from the high-spin state (HS-1) at 292 K through the spin crossover at about 235 K to the low-spin state at 100 K (LS-1) the iron coordination environment changed to a more regular octahedral geometry and the Fe-N bond lengths decreased by 0.216 and 0.196 A (Fe-N(phen)) and 0.147 A (Fe-N(CSe)). When the low-spin state was illuminated with visible light at about 26 K, the structure of this LIESST induced metastable high-spin state (HS-2) was very similar to that of HS-1 with regards to the Fe-phen bond lengths, but there were some differences in the bond lengths in the Fe-NCSe unit between HS-1 and HS-2. When HS-2 was warmed in the dark to 50 K, the resultant low-spin state (LS-2) had an essentially identical structure to LS-1. In all spin states, all of the shortest intermolecular contacts (in terms of van der Waals radii) involved the NCSe ligand, which may be important in describing the cooperativity in the solid state. The quality of the samples was confirmed by magnetic susceptibility and IR measurements.

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“…For [Fe(phen) 2 (NCS) 2 ] the abrupt spin crossover ( 5 T 2 high spin to 1 A 1 low spin) § near 175 K has been investigated by a variety of means, including magnetic susceptibility 2-9 and calorimetric 7,10,11 measurements, 57 Fe Mössbauer, 3,4,6,7,12, 13 IR, 4,10,13-16 UV/VIS, 4,9 NMR, 12,17 ESR, 18 X-ray photoelectron (XPS) 19, 20 and muon 21 spectroscopic techniques. In addition to X-ray powder diffraction, 2-5, 7 single-crystal X-ray diffraction has been used to study the structural changes associated with temperature- 22 or pressure-23 induced spin transitions. Iron K-edge X-ray absorption fine structure spectroscopy (XAFS) has been used to monitor the structural modifications both on cooling 24-27 and on increasing pressure.…”

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confidence: 99%

Soft X-ray induced excited spin state trapping and soft X-ray photochemistry at the iron L2,3 edge in [Fe(phen)2(NCS)2] and [Fe(phen)2(NCSe)2] (phen = 1,10-phenanthroline) ‡

Collison¹,

Garner²,

McGrath³

et al. 1997

J. Chem. Soc., Dalton Trans.

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Further studies on the spin cross-over phenomenon in di-isothiocyanatobis(1,10-phenanthroline)iron(II)

Cited by 50 publications

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Phenomenological model of spin crossover in molecular crystals as derived from atom–atom potentials

Phenomenological model of spin crossover in molecular crystals as derived from atom–atom potentials

Structural Study of the Thermal and Photochemical Spin States in the Spin Crossover Complex [Fe(phen)₂(NCSe)₂]

Soft X-ray induced excited spin state trapping and soft X-ray photochemistry at the iron L2,3 edge in [Fe(phen)2(NCS)2] and [Fe(phen)2(NCSe)2] (phen = 1,10-phenanthroline) ‡

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Further studies on the spin cross-over phenomenon in di-isothiocyanatobis(1,10-phenanthroline)iron(II)

Cited by 50 publications

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Phenomenological model of spin crossover in molecular crystals as derived from atom–atom potentials

Phenomenological model of spin crossover in molecular crystals as derived from atom–atom potentials

Structural Study of the Thermal and Photochemical Spin States in the Spin Crossover Complex [Fe(phen)2(NCSe)2]

Soft X-ray induced excited spin state trapping and soft X-ray photochemistry at the iron L2,3 edge in [Fe(phen)2(NCS)2] and [Fe(phen)2(NCSe)2] (phen = 1,10-phenanthroline) ‡

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Structural Study of the Thermal and Photochemical Spin States in the Spin Crossover Complex [Fe(phen)₂(NCSe)₂]