Reaction of PtCl2(2,2’-bipyridine) (1) with equimolar amounts of N-acetyl-L-cysteine (L-accysH), mercaptopropanoic acid (mpaH), 2-aminoethanethiol (aetH), or cysteine (cysH) in water at pH 7 leads to the isolation of [Pt-2(mu-L-S)(2)(bpy)(2)] (L = L-accys (2), mpa (3), aet (4), cys (5)). The molecular structure of 2 was determined through a single-crystal X-ray diffraction study. Crystallographic data for 2 .4H2O : monoclinic C2, Z = 4, a = 19.491(4) Angstrom, b = 19.266(4) Angstrom, c = 11.494(2) Angstrom, beta = 102.88(3)degrees, V = 4208(2) Angstrom(3). The H-1 and C-13({H-1}) NMR spectra of 2-5 in D2O solution are consistent with a mu-S dimeric formulation. The spectra of 2 and 5 are more complex than those of 3 and 4 due to the presence of chiral ligands. The eta(2)-N,S monomeric complexes Pt(eta(2)-L-N,S)(bpy) (L = aet (7), cys (8)) are produced upon adjusting an aqueous solution of 4 and 5 to pH 11 or directly from the reaction of 1 with aet or cys at pH 11. Complexes 7 and 8 were characterized through H-1 and C-13{H-1} NMR spectroscopy. The similar chemical shifts observed in Pt-195 NMR spectroscopic studies of the mu-S dimer complexes 2 and 4 are markedly different than that observed for the eta 2-N,S monomeric complex 7. Reaction of 1 with penicillamine (pen) and penicillamine methyl ester (penOMe) in aqueous solution at pH 7 gives rise to Pt-2(mu-pen-S)(2)(bpy)(2) (9) and Pt-2(mu-penOMe-S)(2)(bpy)(2) (11), respectively. H-1 NMR spectroscopic studies of 9 and 11 indicate the complexes to have mu-S dimeric rather than eta(2)-N,S or eta(2)-O,S monomeric structures. Heating an aqueous solution of 5 at 70 degrees C results in its conversion to the eta(2)-N,S monomeric complex 8. In contrast, both 4 and 11 are stable at 80 degrees C suggesting thermal conversion of 5 to 8 proceeds through deprotonation of the amine group via a N-O proton transfer. Reaction of 1 with pen at pH 11 produces Pt(eta 2-pen-N,S)(bpy) (10). The structural similarity of 10 to 7 and 8 is evident through comparison of the aromatic region of H-1 NMR spectra of 10.