Stereospecific synthesis and redox properties of ruthenium(II) carbonyl complexes bearing a redox-active 1,8-naphthyridine unit

Two stereoisomers of cis-[Ru(bpy)(pynp)(CO)Cl]PF6 (bpy = 2,2′-bipyridine, pynp = 2-(2-pyridyl)-1,8-naphthyridine) were selectively prepared. The pyridyl rings of the pynp ligand in [Ru(bpy)(pynp)(CO)Cl]+ are situated trans and cis, respectively, to the CO ligand. The corresponding CH3CN complex ([Ru(bpy)(pynp)(CO)(CH3CN)]2+) was also prepared by replacement reactions of the chlorido ligand in CH3CN. Using these complexes, ligand-centered redox behavior was studied by electrochemical and spectroelectrochemical techniques. The molecular structures of pynp-containing complexes (two stereoisomers of [Ru(bpy)(pynp)(CO)Cl]PF6 and [Ru(pynp)2(CO)Cl]PF6) were determined by X-ray structure analyses.

Three complexes containing the 1,8-naphthyridine-based unsymmetrical ligand ([Ru(bpy)(pynp)(CO)Cl]+, [Ru(pynp)2(CO)Cl]+ and [Ru(bpy)(pynp)(CO)(CH3CN)]2+: bpy = 2,2′-bipyridine, pynp = 2-(2-pyridyl)-1,8-naphthyridine) were prepared. A suitable synthetic method for selective formation of stereoisomers was established. Ligand-centered redox reactions were studied by electrochemical and spectroelectrochemical techniques.Figure optionsDownload as PowerPoint slideHighlights
► Three complexes with the 1,8-naphthyridyl-based unsymmetrical ligand were prepared.
► A synthetic method for selective formation of stereoisomers was established.
► No structural changes occurred by the ligand-based redox reaction of the complexes.