• Ruthenium;
  • N ligands;
  • Poly­pyridyl complexes;
  • Thiophenes;
  • Electrophilic addition;
  • Cyclic voltammetry


In this contribution, we report the synthesis, the characterization and the study of the electrochemical and photophysical properties of some novel mononuclear RuII–polypyridyl complexes of the general formula [Ru(tpy)(bpy)L]+ (tpy = 2,2′:6′,2"-terpyridine, bpy = 2,2′-bipyridyl) in which L is represented by 5-(2-thienyl)tetrazolate-type ligands. In addition, the reactivity of these mononuclear species toward different electrophiles such as H+ and CH3+ has been investigated, and the effects of the resulting regioselective electrophilic attacks on the electronic and structural properties of the tetrazolate ligand have been studied by NMR (1H, 13C) spectroscopy and X-ray crystal structural determination. Also, the electronic properties of the complexes have been explored by means of absorption and emission spectroscopy, together with a detailed electrochemical investigation combined with density functional theory (DFT) calculations. The data obtained from the study of such “model” mononuclear species constituted the basis for the characterization of the corresponding bithienyl-bridged dinuclear RuII complex, which displayed similar physical–chemical properties and an analogous behaviour toward the addition of electrophilic agents.