Synthesis, Isolation, and Structural Characterization of the C4h Isomer of Metal(1,2-naphthalocyanine) and Its One-Dimensional Conductor of the Axially Substituted Species

The C4h isomer of the 1,2-Nc (1,2-naphthalocyaninato) ligand has been efficiently isolated as a hydrated magnesium complex by the fractional crystallization from the benzene/acetone solution after treating the crude mixture of the four isomers (C4h, Cs, C2v, D2h) with benzene. The C4h symmetry has been confirmed by X-ray structure analysis. The central metal ion has been demetalated and subsequently converted to the Li2 complex followed by conversion to the cobalt(II) complex. Electrochemical oxidation of the CoIII(1,2-Nc)(CN)2 anion prepared from the cobalt(II) complex with TPP (tetraphenylphosphonium) has yielded a partially oxidized salt, TPP[CoIII(1,2-Nc-C4h)(CN)2]2. The crystal comprises slipped stacked CoIII(1,2-Nc-C4h)(CN)2 one-dimensional chains and one-dimensional arrays of TPPs. The conductivity at room temperature is 0.1 S cm-1, and the temperature dependence is semiconducting with a small activation energy of about 0.05 eV. The positive temperature-independent value of about 60 μV deg-1 observed in the thermoelectric power measurements suggests that the salt is in the correlated hopping regime.