Electrochemical Preparation and Characterization of the Radical Salts of (Phthalocyaninato)nickel, NiPc(SbF6)0.5, and NiPc(AsF6)0.5

Abstract

The single crystals of NiPc(SbF6)0.5 and NiPc(AsF6)0.5 were prepared by means of an electrochemical method. The electrical, magnetic, optical, and structural properties of these crystals were examined. These crystals are isostructural to each other, and exhibit a metallic behavior at least above 200 K. The g-values of the ESR signals remarkably depend upon temperature. By the aid of the low temperature experiments of XANES and reflectance spectrum, the temperature dependence is explained by the model based on the interaction between the small amount of local spins on the Ni atoms and the conduction electrons on the ligand chain. In addition, a sample dependence was found on the ESR properties of the crystals of NiPc(AsF6)0.5. This is attributed to the sample dependence of the concentration of the local spins on Ni atoms. From these considerations, we concluded that the ligand part is mainly oxidized in these partially oxidized salts, in other words the conduction electrons are located on the ligand chain. The bandwidth of the conduction band was estimated to be about 1 eV.