Synthesis, structure, redox property and ligand replacement reaction of ruthenium(II) complexes containing a terpyridyl ligand with a redox active moiety

Ruthenium(II) complexes bearing a redox-active tridentate ligand 4'-(2,5-dimethoxyphenyl)-2,2':6',2 ''-terpyridine (tpyOMe), analogous to terpyridine, and 2,2'-bipyridine (bpy) were synthesized by the sequential replacement of Cl by CH(3)CN and CO on the complex. The new ruthenium complexes were characterized by various methods including IR and NMR. The molecular structures of [Ru(tpyOMe)(bpy)(CH(3)CN)](2+) and two kinds of [Ru(tpyOMe)(bpy)(CO)](2+) were determined by X-ray crystallography. The incorporation of monodentate ligands (Cl, CH(3)CN and CO) regulated the energy levels of the MLCT transitions and the metal-centered redox potentials of the complexes. The kinetic data observed in this study indicates that the ligand replacement reaction of [Ru(tpyOMe)(bpy)Cl](+) to [Ru(tpyOMe)(bpy)(CH(3)CN)](2+) proceeds by a solvent-assisted dissociation process. (C) 2009 Elsevier Ltd. All rights reserved.