Magnetic Bistability and Single-Crystal-to-Single-Crystal Transformation Induced by Guest Desorption

An iron(II) complex with ferrocenyl groups, [Fe(dppFc)2](BF4)2·2Et2O (1·2Et2O, dppFc = 1-ferrocenyl-2-{(2,6-bis(pyrazolyl)pyridyl}ethylene), was prepared. X-ray crystallographic analyses revealed that 1·2Et2O underwent a single-crystal-to-single-crystal transformation with the release of crystal solvent molecules. In magnetic susceptibility measurements, a reversible conversion between paramagnetism and spin-crossover induced by solvent molecules was observed.