Unusual spin-transition anomaly in the crossover system [Fe(2-pic)3]Cl2·EtOH

Abstract The spin transition in [Fe(2-pic) 3 ]Cl 2 ·EtOH (2-pic = 2-picolylamine) has been reinvestigated by Mossbauer spectroscopy and magnetic susceptibility measurements. With both techniques we see a “two-step” spin conversion in the crossover region with transition temperatures at 120.7 and 114.0 K. This has never been reported for any other spin crossover system. The quadrupole splittings for both spin states change abruptly in the range of the transition.