Stereochemistry of New Nitrogen-Containing Heterocyclic Aldehydes. XII. Supramolecular Structures and Properties Models of Ruthenium with Quinoline Azodyes

Novel bis- and tris-complexes of ruthenium(III) with 5-(4′-derivative phenyldiazo)-8-hydroxy-7-quinolinecarboxaldehyde (HL n) have been characterised on the basis of elemental and thermal analysis, IR, magnetic and electronic spectral analysis as well as conductivity measurements. Electronic spectra show that all complexes are octahedral with chloride are attached to the metal ion in a 1:2 (metal:ligand) ratio. The spectral data were utilised to compute the ligand field parameters B, β and Dq. The B-values suggest a strong covalency in the metal-ligand σ-bond and the Dq-values indicate a medium-strong ligand field. It is apparent that the β values depend greatly upon the electronegativity of the donor atoms and the ligand structure and also the effect of the p-substituent groups. IR spectra indicate that the ligand is bidentate forming a six-membered chelating ring with concomitant formation of an intramolecular hydrogen bond. The ligands are present in associated form in solution via intermolecular hydrogen bonding. The effect of Hammett's constant on the ligand field parameters is also discussed.