MILIN, Eric; BENAICHA, Bouabdellah; EL HAJI, Fatima; PATINEC, Véronique; TRIKI, Smail; MARCHIVIE, Mathieu; GÓMEZ-GARCÍA, Carlos J.; PILLET, Sébastien

doi:10.1002/ejic.201600660

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MILIN, Eric
Chimie, Electrochimie Moléculaires et Chimie Analytique [CEMCA]

BENAICHA, Bouabdellah
Chimie, Electrochimie Moléculaires et Chimie Analytique [CEMCA]

EL HAJI, Fatima
Chimie, Electrochimie Moléculaires et Chimie Analytique [CEMCA]

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Article de revue

Ce document a été publié dans

European Journal of Inorganic Chemistry. 2016 n° 34, p. 5305-5314

Wiley-VCH Verlag

Résumé en anglais

Two new iron(II) complexes of formula [Fe(L2)](tcm)2·2H2O (1) and [Fe(L2)][Ni(CN)4]·H2O (2) {L2 = 1,8-bis(2′-pyridylmethyl)-1,4,8,11-tetraazacyclotetradecane; tcm– = [C(CN)3]– = tricyanomethanide anion} have been synthesized and characterized by X-ray diffraction and magnetic measurements and compared with the previously described compound of the same series [Fe(L2)](BF4)2·H2O (3). The crystal structures of the three compounds show discrete iron(II) complexes in which the FeII ions adopt distorted FeN6 octahedral geometries. A hydrogen-bonding network involving the water molecules and the different counter ions, tcm– in 1 and [Ni(CN)4]2– in 2, leads to chains for both compounds whereas compound 3 reveals no significant intermolecular contacts. For 1, the magnetic measurements show an abrupt and incomplete high-spin→low-spin (HS→LS) spin transition (ST) with a hysteresis of 9 K (T1/2down = 136 K; T1/2up = 145 K) that is also optically observed. Compound 2 presents slightly weaker intermolecular contacts and shows an abrupt ST at 85 K without hysteretic behaviour. Finally, compound 3, in which the FeII complex is well isolated, exhibits a gradual spin transition centred at 150 K. Detailed X-ray diffraction studies performed at various temperatures (293–120 K) show strong modifications of the iron coordination sphere in 1 and 3, in agreement with the presence of a ST in this temperature range in both complexes.< Réduire

Mots clés en anglais

Macrocyclic ligands · N ligands · Iron · Spin crossover · Magnetic properties

DOI

http://dx.doi.org/10.1002/ejic.201600660

Project ANR

Bistabilité magnétique dans de nouveaux systèmes moléculaires à base de ligands anioniques pontants - ANR-12-BS07-0030

Origine

Importé de hal

Unités de recherche

Institut de Chimie de la Matière Condensée de Bordeaux (ICMCB) - UMR 5026