Variation of Spin-Transition Temperature in the Iron(III) Complex Induced by Different Compositions of the Crystallization Solvent

Abstract

We crystallized the Schiff-base iron(III) spin-crossover complex [Fe(3,5Cl-L5)(NCSe)] from different two-component solvent mixtures containing methanol and chloroform (Φ = V(CH3OH)/V(solvent) = 0.05, 0.25, 0.50, 0.83, and 1.00). The obtained crystalline products were characterized by X-ray diffraction, and it was confirmed that they are all composed of the same crystalline phase, and they do not contain any crystal solvent. However, significant differences in magnetic properties were observed, and thermal hysteresis changed from (in K) 121T↓ and 134T↑ for Φ = 0.05 and 0.25, down to 72T↓ and 96T↑ for Φ = 1.00. The crystal structures of the low-spin and high-spin phases were studied theoretically and experimentally.