EXAFS Study of the Liquid Crystalline Phase of the Cyclopalladated 4-4'-bis(hexyloxy)azoxybenzene Acetylacetonate Complex

An EXAFS study of the mononuclear nematogenic cyclopalladated 4,4′-bis(hexyloxy)azoxybenzene complex in its liquid-crystalline phase is reported, aimed at exploring the metal coordination environment and confirming either the nature of intermolecular correlations or the presence of polar multimers. The interatomic distances between the palladium center and the atoms of the first coordination shell have been determined with an accuracy better than 10-2 A. The results of the data analysis also indicate that the intermolecular interactions, if any, are very weak and do not involve the palladium(II) coordination sphere. In addition, they suggest that the aggregation model previously proposed to account for the ferroelectric behavior of this compound has to be revised to consider the possibility of either van der Waals and/or polar intermolecular interactions or a peculiar packing mode imposed by the P-shaped molecular geometry.