Ruthenium(II) Arene Complexes Bearing Tris(pyrazolyl)methanesulfonate Capping Ligands. Electrochemistry, Spectroscopic, and X-ray Structural Characterization

Novel [Ru­(L)­(Tpms)]Cl and [Ru­(L)­(TpmsPh)]­Cl complexes (L = p-cymene, benzene, or hexamethylbenzene, Tpms = tris­(pyrazolyl)­methanesulfonate, TpmsPh = tris­(3-phenylpyrazolyl)­methanesulfonate) have been prepared by reaction of [Ru­(L)­(μ-Cl)2]2 with Li­[Tpms] and Li­[TpmsPh], respectively. [Ru­(p-cymene)­(Tpms)]­BF4 has been synthesized through a metathetic reaction of [Ru­(p-cymene)­(Tpms)]Cl with AgBF4. [RuCl­(cod)­(Tpms)] (cod = 1,5-cyclooctadiene) and [RuCl­(cod)­(TpmsPh)] are also reported, being obtained by reaction of [RuCl2(cod)­(MeCN)2] with Li­[Tpms] and Li­[TpmsPh], respectively. The structures of the complexes and the coordination modes of the ligands have been established by IR, NMR, and single-crystal X-ray diffraction (for [RuL­(Tpms)]­X (L = p-cymene or HMB, X = Cl; L = p-cymene, X = BF4)) studies. Electrochemical studies showed that each complex undergoes a single-electron RuII → RuIII oxidation at a potential measured by cyclic voltammetry, allowing to compare the electron-donor characters of the tris­(pyrazolyl)­methanesulfonate and arene ligands, and to estimate, for the first time, the values of the Lever EL ligand parameter for TmpsPh, HMB, and cod.