Multi-Dimensional Stacking Structures in Phthalocyanine-Based Electrical Conductors, K[Co(phthalocyaninato)(CN)2]2·5CH3CN and Co(phthalocyaninato)(CN)2·2H2O

Two kinds of electrically conducting crystals have been obtained by the electrochemical oxidation of potassium dicyanophthalocyaninatocobalt(III), KCo(Pc)(CN)2. Oxidation in acetonitrile gives K[Co(Pc)(CN)2]2·5CH3CN, in which the phthalocyanine rings are two-dimensionally stacked. Since some of the acetonitrile molecules can be easily removed from the lattice, the crystal is not stable outside of the solution. Mosaically distorted crystals, which are exposed to air, show relatively high conductivities (≈10 Ω−1cm−1 at room temperature). On the other hand, oxidation in benzonitrile in the presence of dibenzo-18-crown-6 yields Co(Pc)(CN)2·2H2O, in which the phthalocyanine rings are three-dimensionally stacked. The water molecules in this crystal form hydrogen bonds, and the crystal is stable against drying. The conductivity of this crystal is ≈1 Ω−1cm−1 at room temperature. The multi-dimensionalities observed in these two kinds of crystals arise from a slipped stacking of phthalocyanine, due to steric interactions of the axial substituents.