Stereochemistry of new nitrogen containing heterocyclic aldehyde. VIII. Spectral and coordination modes of mixed-ligand of novel ruthenium(III) complexes.

Reaction of 8-hydroxy-7-quinolinecarboxaldehyde (LH) with RuC3 x XH2O afforded the compounds [RuL3] and/or [RuL2CIOH2]. Reactions of LH with RuCl3 x XH2O in the presence of N-heterocyclic bases led to the formation of complexes of type [RuL2 x ClPy] and [RuLCl2(o-Phen)] (Py = pyridine or o-Phen = 1,10-phenanthroline). The amine exchange reactions of coordinated Schiff bases in these complexes have been also carried out which give symmetrical tetradentate Schiff base complexes. These complexes were characterized by a combination of elemental analysis, IR, magnetic susceptibility measurements, 1H, 13C NMR and electronic spectral analysis methods. The spectral data were utilized to compute the important ligand field parameters B, beta and Dq. Electronic spectra show all complexes are octahedral. The B-values suggest a strong covalency in the metal-ligand sigma-bond and the Dq-values indicate a medium-strong ligand field. The stereochemistry and the nature of the complexes are markedly dependent upon the molar ratios of the reactants, the pH of the system and the nature of the anions involved. The ligands behave as bi-(0,0) and tetradentate (N2,O2) donors.