Spin transition in a ferrous chloride complex supported by a pentapyridine ligand

Ferrous chloride complexes [FeIILxCl] commonly attain the high-spin state independently of the supporting ligand(s) and temperature. Herein, we present the first report of a complete spin crossover with T1/2 = 80 K in [FeII(Py5OH)Cl]+ (Py5OH = pyridine‐2,6‐diylbis[di(pyridin‐2‐yl)methanol]). Both spin forms of the complex are analyzed by X-ray spectroscopy and DFT calculations.