Bis(bipyridine)ruthenium(II) complexes with an aliphatic sulfinato donor: synthesis, characterization, and properties.

Treatment of a thiolato-bridged Ru(II)Ag(I)Ru(II) trinuclear complex, Ag{Ru(aet)(bpy)(2)}(2) (aet = 2-aminoethanthiolate; bpy = 2,2'-bipyridine), with NaI in aqueous ethanol under an aerobic condition afforded a mononuclear ruthenium(II) complex having an S-bonded sulfinato group, 1 (Ru(aesi-N, S)(bpy)(2) (aesi = 2-aminoethanesulfinate)). Similar treatment of optically active isomers of an analogous Ru(II)Ag(I)Ru(II) trinuclear complex, Δ(D)Δ(D)- and Λ(D)Λ(D)-Ag{Ru(d-Hpen-O,S)(bpy)(2)}(2) (d-pen = d-penicillaminate), with NaI also produced mononuclear ruthenium(II) isomers with an S-bonded sulfinato group, Δ(D)- and Λ(D)-2 (Ru(d-Hpsi-O,S)(bpy)(2) (d-psi = d-penicillaminesulfinate)), respectively, retaining the bidentate-O,S coordination mode of a d-Hpen ligand and the absolute configuration (Δ or Λ) about a Ru(II) center. On refluxing in water, the Δ(D) isomer of 2 underwent a linkage isomerization to form Δ(D)-[3] (+) (Ru(d-Hpsi-N,S)(bpy)(2)), in which a d-Hpsi ligand coordinates to a Ru(II) center in a bidentate-N,S mode. Complexes 1, Δ(D)- and Λ(D)-2, and Δ(D)-3 were fully characterized by electronic absorption, CD, NMR, and IR spectroscopies, together with single-crystal X-ray crystallography. The electrochemical properties of these complexes, which are highly dependent on the coordination mode of sulfinate ligands, are also described.