1H, 13C NMR and UV spectroscopy studies of gold(III)-tetracyanide complex with l-cysteine, glutathione, captopril, l-methionine and dl-seleno-methionine in aqueous solution

Auricyanide [Au(CN)4]− interaction with biologically important thiols, thioether and selenoether were carried out and monitored using 1H, 13C NMR and UV spectroscopy. These ligands include l-cysteine, glutathione, captopril, l-methionine and dl-seleno-methionine. Thiols show very strong affinity to be oxidized into the disulfide by auricyanide, which gets reduced to aurocyanide [Au(CN)2]−. l-cysteine reaction mechanism with [Au(CN)4]− was found to be dependent on reactants mole ratio. While l-methionine was completely inert toward auricyanide, dl-Se-methionine showed some reactivity with [Au(CN)4]− after raising solution pH to 12 that facilitated cyanide exchange.