One-dimensional phthalocyanine-based conductor with S = 3/2 isotropic magnetic centers

Abstract

The axially ligated phthalocyanine conductor of TPP [ Cr ( Pc )( CN )2]2 (TPP = tetraphenylphosphonium and Pc = phthalocyaninato) with d3 (S = 3/2) metal Cr III has been successfully prepared. The crystal is completely isomorphous with those of the Co and Fe analogs, and the degree of π–π interaction is almost the same in these three salts. The electrical conductivity at room temperature of the Cr system is almost the same with that of the Fe system in which S = 1/2 magnetic centers embedded in the conduction path, and the temperature dependence reveals the development of the charge disproportionation reflecting the existence of magnetic moments. Magnetic susceptibility of the Cr system shows Curie-like behavior with isotropic local moments of S = 3/2. In contrast with the Fe system, only weak antiferromagnetic interaction operates between the localized d-spins. The resistance decreases when magnetic fields are applied, but the magnetoresistance effect is not so large compared with the Fe system, indicating that the π– d interaction in the Cr system is somewhat different from that in the Fe system.