| Abstract: | The mesomorphic 4,4-bis4-n-octyloxybenzoyloxy]azobenzene dinuclear chloro-bridged cycloplatinated complex (Azo)Pt(mu;-Cl)]2 (smectic C between 263 and 342 C) has been reacted with different chelating ligands, giving rise to a family of square-planar ortho-platinated derivatives, (Azo)Pt(L)] (L = tropolonate, 8-hydroxyquinolinate and 1,1,1,5,5,5-hexafluoro2,4-pentanedionate). Thermotropic mesomorphism is preserved for these mononuclear complexes which exhibit at least a nematic mesophase and transition temperatures lower by over 100° C than that of the corresponding dimeric precursor. Oxidative addition to the Pt(II) (Azo)Pt(L)] species of electrophilic substrates such as I2 or CH3I eventually led to the corresponding octahedral (Azo)Pt(L)(I )(X)] products. The introduction of two further ligands leads to Pt(IV) derivatives showing smectic and nematic mesophases for all L ligands. For the hexacoordinated (Azo)Pt(L)(I)(CH3)] complexes it has been verified that the oxidative addition of methyl iodide is a thermally reversible process, indicating that these species have potential applications as switchable systems. |
