Synthesis and characterisation of some Ru(II) complexes of 2-carbamoylpyridine derivatives

p-Substituted N-phenyl derivatives of 2-carbamoylpyridine (L) have been prepared by the reaction of pyridine-2-carboxylic acid with p-substituted aniline. Five complexes of the type [Ru(L)(DMSO)(2)Cl-2] have been synthesized by the reaction of [Ru(DMSO)(4)Cl-2] with L. The amide ligands have been characterized by elemental analysis, infra red and H-1 NMR spectral studies. The complexes are diamagnetic and show intense absorptions due to metal to ligand charge transfer (MLCT) transitions in the UV-visible spectra. The IR spectra of the complexes show that the amide ligands coordinate to the ruthenium (II) ion as a bidentate ligand coordinating from pyridyl nitrogen and from the carbonyl oxygen of the amide group. The complexes undergo a reversible ruthenium (II)-ruthenium (III) oxidation near 0.55 V in acetonitrile solution. The ruthenium (II)-ruthenium (III) oxidation potentials of the complexes are found to be sensitive to the nature of the substituent on the ligand. (C) 1999 Elsevier Science Ltd. All rights reserved.