An iron(II) complex with ferrocenyl groups, [Fe(dppFc)(2)](BF4)(2)center dot 2Et(2)O (1 center dot 2Et(2)O, dppFc = 1-ferrocenyl-2-{(2,6-bis(pyrazolyl)pyridyl}ethylene), was prepared. X-ray crystallographic analyses revealed that 1 center dot 2Et(2)O 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.