Temperature-Induced Single-Crystal-to-Single-Crystal Transformations with Consequential Changes in the Magnetic Properties of Fe(III) Complexes.

The present article deals with an one-to-one structure-property correspondence of a dinuclear iron complex, [Dipic(HO)FeOH]·HO () (Dipic = pyridine-2,6-dicarboxylic acid). Variable-temperature X-ray single-crystal structural analysis confirms a phase transition of complex to complex ([Dipic(HO)FeOH]) 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 crystallizes in the 2/ space group, whereas complex crystallizes in the space group. SCSC transformation brings the change in packing diagram as well. Complex shows two-dimensional network through H-bonding, whereas the packing diagram of complex 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.