Treatment of a thiolato-bridged Run(II)Ag(I)Ru(II) trinuclear complex, [Ag{Ru(aet)(bpy)(2)}(2)](3+) (aet = 2-arninoethanthiolate; 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 Run(II)Ag(I)Ru(II) trinuclear complex, Delta(D)Delta(D)- and Lambda(D)Lambda(D)-[Ag{Ru(D-Hpen-O,S)(bpy)(2)}(2)](3+) (D-pen = D-penicillaminate), with NaI also produced mononuclear ruthenium(II) isomers with an S-bonded sulfinato group, Delta(D)- and Lambda(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 (Delta or Lambda) about a Ru-II center. On refluxing in water, the Delta(D) isomer of [2](+) underwent a linkage isomerization to form Delta(D)-[3](+) ([Ru(D-Hpsi-N,S)(bpy)(2)](+)), in which a D-Hpsi ligand coordinates to a Run(II) center in a bidentate-N,S mode. Complexes [1](+), Delta(D)- and Lambda(D)-[2](+), and Delta(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.