One-dimensional π–d electron system in TPP[Fe(Pc)(CN)2]2, [PXX][Fe(Pc)(CN)2], and (PTMA)x[Fe(Pc)(CN)2]Y(CH3CN): electron spin resonance and negative magnetoresistance

We measured the electron spin resonance and the magnetoresistance in the iron(III) phthalocyanine complexes. The electron spin resonance in PNP[Fe(Pc)(CN)2] reveals the large anisotropy of the g-value. This is due to the strong spin–orbit coupling in the second HOMO (the third HOMO) hybridizing the dyz (dzx) orbital in the central Fe atom. This anisotropic g-value is consistent with the anisotropy of the magnetic susceptibility and the negative magnetoresistance in TPP[Fe(Pc)(CN)2]2. We also measured the large negative magnetoresistance in [PXX][Fe(Pc)(CN)2] and (PTMA)x[Fe(Pc)(CN)2]Y(CH3CN). The iron(III) phthalocyanine complexes are the good materials for the research of the one-dimensional π–d electron system.