Thermal and light-induced spin-crossover in salts of the heptadentate complex [tris(4-{pyrazol-3-yl}-3-aza-3-butenyl)amine]iron(II)
Résumé
The syntheses of [FeL][BF4]2·H2O, [FeL][ClO4]2·H2O, [FeL][NO3]2·CH3NO2 and [FeL][CF3SO3]2 (L = tris(4-{pyrazol-3-yl}-3-aza-3-butenyl)amine) are described. The isostructural BF4– and ClO4– salts are high-spin between 5–300 K, while the other two compounds are high-spin at room temperature but undergo gradual high -> low spin transitions upon cooling. For [FeL][NO3]2 this transition is centred at 139 K and proceeds to near-completeness, while for [FeL][CF3SO3]2 it is centred at 144 K and only proceeds to 50% conversion...