Abstract

A series of Fe^III complexes, [Fe(qsal-5-OMe)<inf>2</inf>]Y [Y = BF<inf>4</inf> (1), PF<inf>6</inf> (2), NCS (3), BPh<inf>4</inf> (4)], have been prepared and structurally and magnetically characterized. The low-temperature structures of 1 and 3 as solvent adducts were determined by X-ray crystallography with LS FeIII centres found in both cases. π-π and C-H···π interactions between the cations lead to 2D sheets that are linked to one another through C-H···O and, in the case of 3, C-H···N/S interactions resulting in high cooperativity. Magnetic studies revealed abrupt and gradual spin crossover for 3 and 2, respectively. For 3, spin crossover with possible thermal hysteresis was observed although solvent loss (CH<inf>2</inf>Cl<inf>2</inf>) could occur. In contrast, 1 and 4 were found to be low and high spin only, respectively. The results of Mössbauer spectroscopic studies are consistent with the magnetic susceptibility data and indicate that there are two low-spin FeIII centres in 2. Finally, electrochemical studies showed reversible reduction to FeII at -0.22 V, whereas reversible oxidation of the qsal-5-OMe ligand was found to occur between 1.04-1.06 V. © 2013 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.