Unusual electrochemical and spectroscopic behavior in a ligand-bridged binuclear complex of ruthenium(II): Tetrakis(2,2'-bipyridine)-(mu-2,4,6-tris(2-pyridyl)triazine) diruthenium(II)

The coordination complex [(Ru(bpy)(2))(2)tpt](PF6)(4) (bpy = 2,2'-bipyridine; tpt=2,4,6-tris(2-pyridyl)triazine) has been prepared in 77% yield. Electrochemical characterization has been carried out and the electrochemical properties are compared to the previously characterized mononuclear analogue, [Ru(bpy)(2)tpt](PF6)(2). Spectroelectrochemical results indicate that the first reduction of the binuclear complex occurs at the tpt ligand, but that the second reduction occurs at a bpy ligand. Both complexes are emissive in room temperature acetonitrile solution and their luminescence lifetimes and quantum yields have been determined. The relationship between the electrochemical and spectroscopic properties of this complex and its mononuclear analogue display a trend counter to those of previously reported mono- and binuclear complexes of Ru(II) based on bidentate bridging ligands.