Dinuclear iron(II, III)complexes with a hexadentate ligand [Fe(2)bpmp(L)(2)](BF4)(2) were prepared, where Hbpmp represents 2,6-bis[bis(2-pyridylymethyl)aminomethyl]-4-methylphenol and L is CH3(CH2)(n)COO- or Ph(CH2)(n)COO-. The Mossbauer spectra of the mixed-valence complexes of L=CH3(CH2)(n)COO- with n=0, 1 and 2 consist of two quadrupole doublets due to high-spin iron(II) and high-spin iron(III). However, the complexes with n=3, 4, 5, 6 and 7 show one quadrupole doublet at room temperature, which suggests a delocalized valence state. The complexes of L=Ph(CH2)(n)COO- with n=0, 1, 2 and 3 show localized valence states and those with n=4 and 5 show a delocalized one.