Transition Metal Complexes with Ordered Mesophases: Cyclopalladated Compounds of (p-Ethoxyphenylazo)-p-Phenyl Heptanoate

The synthesis, characterization and thermal behaviour of dinuclear and mononuclear cyclopalladated derivatives of (p-ethoxyphenylazo)-p-phenyl heptanoate are reported. The dinuclear halo-bridged complexes show nematic phases at temperatures increasing in the order CI < Br < I. The breaking of the halogen bridge by pyridine or quinoline affords a new series of mononuclear liquid crystals in which a layered smectic phase is present. The connection between the nature of the neutral nitrogenous ligand and the thermal properties of the mononuclear complexes is also discussed.