New perspectives on the reactions of metal nitrosyls with thiolates as nucleophiles

Abstract The susceptibility of the nitrosonium ligand (NO + ) of metal nitrosyls to nucleophilic attack has been reviewed. The reactions of nitroprusside with thiolate (RS − ) nucleophiles (H 2 S, cysteine, glutathione, N-acetylcysteine and others) have been covered, albeit the main focus is on the reactivity of ruthenium nitrosyl ammines ( trans -[Ru(NH 3 ) 4 (L)NO + ] n + ) with cysteine and glutathione. Kinetic aspects and reaction products are discussed. Nitric oxide (NO) and nitroxyl (HNO) are the primary and main nitrogen-based products of the reactions with RS − . The final nitrogen based product N 2 O is identified and suggested as the direct product from the dimerization reaction of HNO. The accumulated data strongly suggest that the ratio of [NO]/[HNO] formed is dependent on the [RS − ]/[RSH] ratio, which can be controlled by the experimental conditions. Some aspects of thiol-responsive nitric oxide-releasing materials are also discussed.