Influences of temperature, pressure and lattice solvents on the spin transition regime of the polymeric compound [Fe(hyetrz)3]A2.3H2O, with hyetrz = 4-(2'-hydroxyethyl)-1,2,4-troazole and A- = 3-nitrophenylsulfonate

Garcia, Yann;van Koningsbruggen, Petra J.;Lapouyade, René;Fournès, Léopold;Gütlich, Philipp;et.al.
(1998) Chemistry of Materials — Vol. 10, n° 9, p. 2426-2433 (1998)

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  • Garcia, Yannorcid-logoUCLouvain
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  • van Koningsbruggen, Petra J.
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  • Lapouyade, René
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  • Fournès, Léopold
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  • Gütlich, Philipp
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Abstract
[Fe(hyetrz)3](3-nitrophenylsulfonate)2·3H2O (1·3H2O), with hyetrz = 4-(2‘-hydroxyethyl)-1,2,4-triazole, has been synthesized, and its physical properties have been investigated with several techniques, including optical and Mössbauer spectroscopies, magnetism at different pressures up to ca. 9 kbar, thermogravimetry, calorimetry, and X-ray powder diffraction. At room temperature, 1·3H2O is in the low-spin (LS) state and the color is pink. As the compound is heated, the three noncoordinated water molecules are released, and the Fe2+ sites now undergo a transition from low-spin (LS, S = 0) to high-spin (HS, S = 2) states. This transformation, denoted as 1·3H2O (LS) → 1 (HS), is irreversible in a normal atmosphere and is accompanied by a change of color between pink and white. Depending on the rate of increasing temperature, it is possible to observe compound 1 in the metastable LS state. The thermal transformation from this metastable state to the stable HS state is then extremely abrupt, occurring within ca. 1 K. Compound 1 has been found to exhibit a spin transition in the low-temperature range, with T1/2 around 100 K. This transition is cooperative around T1/2, with a thermal hysteresis of about 10 K, but already begins immediately below room temperature. At 4 K, about 15% of the Fe2+ sites have been found to remain in the HS state. The pressure dependence of the LS HS transition for 1 has been investigated. A pronounced effect has been observed; the transition temperature is shifted from 100 to 270 K as the pressure varies from 1 bar up to 8.9 kbar.
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  • Université de Bordeaux (France)Chimie du Solide et Sciences des Matériaux
  • Institution iconUCLouvainAutre

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Garcia, Y., van Koningsbruggen, P. J., Lapouyade, R., Fournès, L., Rabardel, L., Kahn, O., Ksenofontov, V., Levchenko, G., & Gütlich, P. (1998). Influences of temperature, pressure and lattice solvents on the spin transition regime of the polymeric compound [Fe(hyetrz)3]A2.3H2O, with hyetrz = 4-(2′-hydroxyethyl)-1,2,4-troazole and A- = 3-nitrophenylsulfonate. Chemistry of Materials, 10(9), 2426-2433. https://doi.org/10.1021/cm980107+ (Original work published 1998)