New organometallic liquid crystals I. Orthopalladated imine derivatives

The synthesis, characterization and thermal behaviour of 12 dinuclear, orthopalladated complexes derived from Schiff's bases are reported. The complexes are of the type Pd₂(H-X)₂C₆H₃(OR)-C(Z) = N-C₆H₄R'₂] (X = OAc, Cl, Br, SCN; Z = H, CH₃; R' = OR, R; R = C₁₀H₂₁) and ten of them exhibit ordered mesophases (S_C and S_A). The molecules were characterized structurally by I.R. and ¹H N.M.R. spectroscopy in order to elucidate the possible existence of isomers. The connection between their molecular structures and their mesogenic properties is discussed.