A Novel Series of Heteropolynuclear Metallomesogens: Organopalladium Complexes with Ferrocenophane‐Containing Ligands

Ferrocenophane‐containing (Fcph) Schiff's bases p ‐C 12 H 25 O(C 6 H 4 )CH=N(C 6 H 4 )Fcph ( L A H ) and p ‐C 12 H 25 O(C 6 H 4 )COO(C 6 H 4 )CH=N(C 6 H 4 )Fcph ( L B H ) react with palladium(II) acetate to form μ‐acetato‐ and chloro‐bridged dimeric organopalladium complexes. By exchanging acetato‐groups with the chloride anions, μ‐chloro‐bridged heteropolynuclear dimers are obtained that show thermotropic smectic A phases over a temperature range of 198 to 260 °C. The complexes [PdClL A ] 2 and [PdClL B ] 2 can be transformed into a variety of mixed‐ligand Pd II complexes by treatment with salicylaldimine p ‐C 12 H 25 O(C 6 H 4 )COO(C 6 H 3 )(OH)CH=N(C 6 H 4 )Fcph ( L C H ) and β‐aminovinyl ketone p ‐C 12 H 25 O(C 6 H 4 )COCH=CHNH(C 6 H 4 )Fcph ( L D H ). The obtained mixed‐ligand heterometallic complexes [PdL A L C ] , [PdL B L C ] , [PdL A L D ] and [PdL B L D ] exhibit enantiotropic, thermotropic nematic phases over a broad temperature range from 71 to 205 °C. The structures of the synthesized compounds were characterized by means of 1 H NMR, IR and UV spectroscopy, as well as elemental analysis. The liquid crystalline properties were studied by polarising optical microscopy and DSC. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)