The structure changes and the spin phase transition mechanism of a spin crossover complex, [Fe(2-pic)3]Cl2·EtOH

The crystal structure of the spin crossover complex Fe(2-pic)₃]Cl₂·EtOH in its high spin state (298, 150 K) and low spin state (90 K) has been determined. The crystals are monoclinic, P2₁/c with Z=4 in the two spin states. Pronounced changes in the FeN bond distance (2.195 A for high spin, 2.013 A for low spin on average) and orientational disorder of the ethanol molecule were observed. The complexes and ethanols are both hydrogen bounded to Cl^? ions.