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[摘要]：A new synthesis of (8-quinolyl)-5-methoxysalicylaldimine (Hqsal-5-OMe) is reported and its crystal structure is presented. Two FeIII complexes, [Fe(qsal-5-OMe)2]Cl.solvent (solvent=2?MeOH.0.5?H2O (1) and MeCN.H2O (2)) have been prepared and their structural, electronic and magnetic properties studied. [Fe(qsal-5-OMe)2] Cl.2?MeOH.0.5?H2O (1) exhibits rare crystallographically independent high-spin and low-spin FeIII centres at 150 K, whereas [Fe(qsal-5-OMe)2]Cl. MeCN.H2O (2) is low spin at 100 K. In both structures there are extensive pp and C?H...p interactions. SQUID magnetometry of 2 reveals an unusual abrupt stepped-spin crossover with T1/2=245 K and 275 K for steps 1 and 2, respectively, with a slight hysteresis of 5 K in the first step and a plateau of 15 K between the steps. In contrast, 1 is found to undergo an abrupt half-spin crossover also with a hysteresis of 10 K. The two compounds are the first FeIII complexes of a substituted qsal ligand to exhibit abrupt spin crossover. These conclusions are supported by 57Fe Mossbauer spectroscopy. Both complexes exhibit reversible reduction to FeII at -0.18 V and irreversible oxidation of the coordinated qsal-5-OMe ligand at +1.10 V. |
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