Crystal Structures and Spin Crossover of Iron(III) Cocrystal FormedviaHalogen Bonding

Abstract

Spin crossover iron(III) compounds containing the tridentate Schiff base ligand and its cocrystal, [Fe(acpa)2]I (1) and [Fe(acpa)2][1,3,5-TITFB(I−)] (2) (Hacpa = N-(1-acetyl-2-propylidene)(2-pyridylmethyl) amine, 1,3,5-TITFB = 1,3,5-triiodotrifluorobenzene), were synthesized and their crystal structures and magnetic properties characterized in detail. 1 exhibits abrupt spin crossover (SCO) behavior (T1/2 = 182 K) with thermal hysteresis loop being 23 K while showing gradual SCO behavior for 2 without thermal hysteresis loop.