Non-classical Fe(II) spin crossover behaviour in polymeric iron(II) compounds of formula [Fe((NH2trz)3]X2.xH2O (NH2trz = 4-amino-1,2,4-triazole ; X = derivatives of naphtalene sulfonate)

van Koningsbruggen, Petra J.;Garcia, Yann;Codjovi, Epiphane;Lapouyade, René;Rabardel, Louis;et.al.
(1997) Journal of Materials Chemistry — Vol. 7, n° 10, p. 2069-2075 (1997)

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Authors
  • van Koningsbruggen, Petra J.
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  • Garcia, Yannorcid-logoUCLouvain
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  • Codjovi, Epiphane
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  • Lapouyade, René
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  • Rabardel, Louis
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Abstract
A new series of iron(ii) spin-crossover materials of formula [Fe(NH2trz)3 ]X2xH2O [X=1-naphthalene sulfonate (1ns), 2-naphthalene sulfonate (2ns), 4-hydroxy-1-naphthalene sulfonate (4OH-1ns), 4-amino-1-naphthalene sulfonate (4NH2-1ns) and 6-hydroxy-2-naphthalene sulfonate (6OH-2ns)] are reported. The structure of these compounds consists of linear chains in which the Fe(ii) ions are linked by triple N1 ,N2-1,2,4-triazole bridges. All compounds show non-classical spin-crossover behaviour. Optical and magnetic measurements recorded upon heating show an abrupt low-spin to high-spin transition accompanied by a pronounced thermochromic effect occuring between 330 and 340 K depending on the anion. Thermogravimetric analyses show that the transition is induced by the removal of the two lattice water molecules, which initially stabilized the low-spin state. The dynamical character of this transition has been monitored by extended 57Fe Mössbauer spectroscopic studies on [Fe(NH2trz)3 ](2ns)2xH2O. Upon cooling, the dehydrated modifications show classical spin-crossover behaviour with hysteresis at much lower temperatures, ranging from 229 to 297 K depending on the anion. [Fe(NH2trz)3 ](2ns)2 represents one of the first iron(ii) spin-crossover materials showing a spin transition in the close vicinity of room temperature (290 K) accompanied by hysteresis (14 K).
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  • Université de Bordeaux (France)Chimie du Solide et Sciences des Matériaux
  • Institution iconUCLouvainAutre

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van Koningsbruggen, P. J., Garcia, Y., Codjovi, E., Lapouyade, R., Kahn, O., Fournès, L., & Rabardel, L. (1997). Non-classical Fe(II) spin crossover behaviour in polymeric iron(II) compounds of formula [Fe((NH2trz)3]X2.xH2O (NH2trz = 4-amino-1,2,4-triazole ; X = derivatives of naphtalene sulfonate). Journal of Materials Chemistry, 7(10), 2069-2075. https://doi.org/10.1039/a702690k (Original work published 1997)