Magnetic properties of V-substitution effect in an iron mixed valence complex

Abstract

The iron mixed-valence complex (n-C3H7)4N[FeIIFeIII(dto)3] (dto=C2O2S2) exhibits a novel type of phase transition according electron transfer between FeII and FeIII called charge transfer phase transition (CTPT). The existence of the CTPT highly depends on the 3d metal substitution with Zn, Mn, Cr, or Co for corresponding Fe site in (n-C3H7)4N[FeIIFeIII(dto)3]. Here, we prepared a series of magnetically diluted complexes (n-C3H7)4N[FeIIFeIII1−xVIIIx(dto)3] (x=0–1), and carried out investigation of magnetic properties. Judging from the magnetic susceptibility measurement, there is no suppression of the CTPT unlike other 3d metal substituted cases. Moreover, 57Fe Mössbauer spectroscopy revealed that about 60% of FeII sites changed their spin states from high spin to low spin in case of substitution rate for x=1.00. Since the difference of hardness and softness between metallic ions (FeII, FeIII and VIII) and coordination sites of ligand (O or S in dto), this behavior is explained by the linkage isomerization of bridging ligand in formation process of the complex.