Bis(bipyridine)ruthenium(II) Complexes with an Aliphatic Sulfinato Donor: Synthesis, Characterization, and Properties

Treatment of a thiolato-bridged RuIIAgIRuII trinuclear complex, [Ag{Ru(aet)(bpy)2}2]3+ (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 RuIIAgIRuII trinuclear complex, ΔDΔD- and ΛDΛD-[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, ΔD- and ΛD-[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 RuII center. On refluxing in water, the ΔD isomer of [2]+ underwent a linkage isomerization to form ΔD-[3] + ([Ru(d-Hpsi-N,S)(bpy)2]+), in which a d-Hpsi ligand coordinates to a RuII center in a bidentate-N,S mode. Complexes [1]+, ΔD- and ΛD-[2]+, and ΔD-[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.