A one-dimensional macrocyclic pi-ligand conductor carrying a magnetic center. Structure and electrical, optical and magnetic properties of TPP[Fe(Pc)(CN)(2)](2) {TPP = tetraphenylphosphonium and [Fe(Pc)(CN)(2)] = dicyano(phthalocyaninato)iron(III)}

A conducting partially oxidized salt of TPP[Fe(Pc)(CN)(2)](2), which contai ns paramagnetic iron(III), has been obtained by electrocrystallization of T PP[Fe(Pc)(CN)(2)]. The crystal is composed of one-dimensional TPP arrays su rrounded by slipped-stacked one-dimensional Fe(Pc)(CN)(2) chains. This stru cture is isomorphous with TPP[Co(Pc)(CN)(2)](2), in which the central metal is non-magnetic cobalt(III). The electrical conductivity at room temperatu re, ca. 10 Omega(-1)cm(-1), is about one order of magnitude lower than that of the Co analogue. On lowering the temperature, the conductivity shows a much steeper decline compared with the temperature dependence of the conduc tivity of TPP[Co(Pc)(CN)(2)](2). The band width, estimated from both thermo electric power measurements (which show apparent metallic behavior at high temperatures) and an extended Huckel calculation, is found to be the same a s that obtained for TPP[Co(Pc)(CN)(2)](2). This is consistent with observat ions from the single-crystal reflectance spectra, in which both partially o xidized salts show almost the same plasma edge. On the other hand, the magn etic susceptibility of TPP[Fe(Pc)(CN)(2)](2) is quite different from that o f TPP[Co(Pc)(CN)(2)](2); both of the magnetic moments originated from Fe-II I and the pi-radical seem to be localized in TPP[Fe(Pc)(CN)(2)](2), while t he moments originated from the pi-radical in TPP[Co(Pc)(CN)(2)](2) are inte racting with each other to lead to temperature-independent Pauli-like susce ptibility. At low temperatures, a decrease in the susceptibility has been o bserved, suggesting the existence of antiferromagnetic interactions.