Three luminescent mononuclear Ru II compounds, [Ru II (bpy) 2 (L 1 )](BF 4 ) (1), [Ru II (bpy) 2 (L 2 )](BF 4 ) (2), and the neutral compound [Ru II (bpy) 2 (L 3 )] (3), were obtained, by treatment of [Ru II (bpy) 2 Cl 2 ] with the tetrazolate (tz)-containing ligands L 1 -L 3 . All the compounds were well characterized by IR, UV/Vis, and 1 H NMR and their redox properties were also investigated by cyclic voltammogram. The crystal structure of 3 was determined by X-ray crystallogra-