Mesogenic Transition Metal Complexes Liquid Crystal Phase Behaviour and Crystal and Molecular Structure of Some Nitrile Complexes of the Platinum Metals

Abstract
A new range of transition metal-containing liquid crystals is formed by complexing classical organic mesogens directly to a metal. Thus, reaction of [PdCl2(PhCN)2] with 4-n-pentyl-4′-cyanobiphenyl (5CB) leads to [PdCl2(5CB)2] which exhibits a monotropic nematic phase. Complexes of long chain 4-alkyloxy-4′-cyanobiphenyls show enantiotropic mesophases. Analogously, reaction of [PtCl2(PhCN)2] or [Rh2Cl2(CO)4] with 4-alkyl-4′-cyanobiphenyls (L) yields mesogenic [PtCl2L2] or cis-[RhCl(CO)2 L] respectively. The crystal and molecular structure of [PdCl2(5CB)2] and [PtCl2(8CB)2] are also reported and show different packing in the solid state.