Supramolecular structural and spectral perspectives of novel ruthenium(III) azodye complexes

Five bis-5-(4′-R-phenylazo)-8-hydroxyquinoline] ruthenium complexes RuLn?·?Cl₂?·?OH₂]; where Ln?=?5-(4′-R-phenylazo)-8-hydroxyquinolinol, R?=?OCH₃ (n?=?1), CH₃(2), H(3), Cl(4), NO₂(5), have been prepared and characterized on the basis of elemental analyses, IR, ¹H NMR, ESR, thermal analysis and magnetic susceptibility measurements. The data show that these complexes exist in trans-isomeric solid form. Two inversion-related ligands and two Ru³⁺ atoms form a cage-like dimer. Both ligands of the dimer are bridged by a pair of inversion-related Ru–N (azodye) bonds. The octahedral coordination geometry of Ru³⁺ is made up of an N of pyridine, the deprotonated quinoline O atom, one of the azodye N atoms, two chlorides and one water. The ligands in the dimer are stacked over one another. In the solid state of azo-8-hydroxyquinoline, the dimers have inter-and intramolecular hydrogen bonds. Interactions between the ligands and the metal are discussed. The azo group was involved in chelation for all the prepared complexes. The effect of Hammet's constant on the ligand field parameters are also discussed and drawn.