Temperature-induced single-crystal-to-single-crystal transformations with consequential changes in the magnetic properties of Fe(III) complexes

Abstract

The present article deals with an one-to-one structure− property correspondence of a dinuclear iron complex, [Dipic(H2O)FeOH]2·H2O (1) (Dipic = pyridine-2,6-dicarboxylic acid). Variable-temperature X-ray single-crystal structural analysis confirms a phase transition of complex 1 to complex 2 ([Dipic(H2O)FeOH]2) at 120 °C. Further, single-crystal-to-single-crystal (SCSC) transformation was monitored by temperature-dependent single crystal X-ray diffraction, powder X-ray diffraction, time-dependent Fourier-transform infrared spectroscopy, and differential scanning calorimetry. SCSC transformation brings the change in space group of single crystal. Complex 1 crystallizes in the C2/c space group, whereas complex 2 crystallizes in the Pi space group. SCSC transformation brings the change in packing diagram as well. Complex 1 shows two-dimensional network through H-bonding, whereas the packing diagram of complex 2 shows a zigzag-like arrangement. Phase transformation not only fetches structural changes but also in the magnetic properties. Difference in Fe−O−Fe bond angles of two complexes creates notable variation in their antiferromagnetic interactions with adjacent metal centers.