Carbon-13 nuclear magnetic resonance studies of the redox reactions of aurothiomalates with selenocyanate in aqueous solution

Abstract

The interactions of SCN^– and SeCN^– with aurothiomalate [Au(tm)]_n in aqueous solution were studied by ¹³C NMR spectroscopy. The [Au(tm)]_n is further polymerized in the presence of SCN^–, however, SeCN^– binds to [Au(tm)]_n forming monomeric [Au(SeCN)(tm)]^–. This complex initially disproportionates to give [Au(SeCN)₂]^– and [Au(tm)₂]^–. The [Au(SeCN)₂]^– eventually decomposed to give [Au(CN)₂]^– and metallic selenium. The free tm^– released from [Au(tm)]_n is oxidized to the thiomalic disulfide (tm)₂. When the bis complex [Au(tm)₂]^– reacted with SeCN^– it did not form [Au(SeCN)(tm)]^–, but instead gave (tm)₂, [Au(CN)₂]^– and Se₂^2–.