Effects of the encapsulation of alkali ions into iron(III) complexes with a macrocyclic ring on magnetic properties

New spin-crossover iron(III) complexes [FeM(salten)L]X with an alkali ion i n a macrocycle have been prepared, and the magnetic properties of the compl exes in the solid and in acetonitrile solution have been examined, where M is Li+, Na+, K+, or Rb+, H-2 salten is 4-aza-heptamethylene-1,7-bis(salicyl ideneiminate) and L is N-(4-picolyl)-aza-15-crown-5-ether. The spin-crossov er behaviors of the iron(III) complexes dependent on temperature in the sol id are observed on the Mossbauer spectra and magnetic susceptibilities, and those in acetonitrile on the electronic spectra. The magnetic properties o f the complexes in the solid are changed with the species of alkali metal i ons included in a macrocycle. Li-complexes show the magnetic moment of 4.00 B.M. at 300 K and 2.19 B.M. at 80 K, and Na-complexes 5.03 B.M. at 300 K a nd 4.21 B.M. at 80 K. The Mossbauer spectra of Li-complexes show that the i nterexchange rates of the spin-state transition between high-spin and low-s pin states are as fast as the reciprocal of the lifetime of the excited sta te of Fe-57(10(-7)s) above 110 K. The magnetic behaviors of all of the comp lexes in acetonitrile are similar.