Sulfur-Based Oxidation

Surprisingly, oxidation of gold(I)-thiolate complexes results in oxidation of sulfur not gold(I). The electrochemistry triggers an unusual n = 0.5 electrochemical process resulting in the formation of disulfide and gold clusters.

PR3Au(I)SR-CV

The formation of clusters has been suggested to happen to the orally active drug, auranofin in the stomach. Gold(I) oxidation does occur but at much higher oxidation potentials; thus under mild oxidation conditions, d-10 gold(I) is not redox active – similar to d-10 Zn (II).shaking_hands_

Chen, J.; Jiang, T.; Wei, G.; Mohamed, A.A.; Homrighausen, C.; Krause Bauer, J.A.; Bruce, A.E.; Bruce, M.R.M. “Electrochemical and Chemical Oxidation of Gold(I) Thiolate Phosphine Complexes: Formation of Gold Clusters and Disulfide”, JACS, 1999, 121, 9225.

Mohamed, A.A.; Bruce, A.E.; Bruce, M.R.M. “Cyclic Voltammetry of Auranofin”, Metal-Based Drugs, 1999, 6, 233.

Mohamed, A.A.; Bruce, A.E.; Bruce, M.R.M. “Electrochemistry of Gold and Silver Complexes”, in Organic Derivatives of Silver and Gold, Patai, S. and Rappaport, Z., Eds., John Wiley & Sons, England, 1999.

Jiang, T.; Wei, G.; Turmel, C.; Bruce, A.E.; Bruce, M.R.M.; “Redox Chemistry of Gold(I) Phosphine Thiolates: Sulfur-Based Oxidation.” Metal Based Drugs, 1994, 1, 419.