Hydrogen-bonded 2D network structure and abrupt spin transition with thermal hysteresis of iron(III) complexes [FeIII(Him)2(3-MeOsalen)]·H2O·EtOH·X (Him = imidazole, 3-MeOsalen = N,N′-bis(3-methoxysalicylidene)ethylenediaminato, and X = PF6, AsF6, SbF6)

Abstract Spin crossover (SCO) iron(III) complexes exhibiting thermal hysteresis, [Fe III (Him) 2 (3-MeOsalen)]·H 2 O·EtOH·X (Him = imidazole, 3-MeOsalen =  N,N′- bis(3-methoxysalicylidene)ethylenediaminato, and X = PF 6 , AsF 6 , SbF 6 ), were synthesized in ethanol. The Fe III ion has an octahedral coordination geometry with N 2 O 2 donor atoms of the planar tetradentate ligand (3-MeOsalen) and two nitrogen atoms of two imidazoles at the axial positions. Through H 2 O and EtOH the complex-cations are assembled into a hydrogen-bonded 2D network structure and the anion X is accommodated in the void of the 2D network. The temperature dependences of the magnetic susceptibilities revealed an abrupt and two-step spin transition with thermal hysteresis for the PF 6 and AsF 6 salts.