Palladium(II) Ion Mediated Disulfide/Thiolate Interconversion: Predicting the Disulfide Group State from First Principles.

Abstract

Different reactivity of homologous disulfides toward Pd2+ was previously reported: stepwise complexation to Pd2+ for l-cystine and cystamine ligands, while for dl-homocystine and 3,3'-dithiodipropionic acid, disulfide's disproportionation toward thiolate and sulfinic acid complexes is observed. The disulfide/thiolate interconversion of four different disulfide ligands in the presence of nonredox metal cation Pd2+ in aqueous solution has been computationally investigated. We see this different reactivity in different capacities of considered homologous disulfides to stabilize forming S,S'-binuclear complexes, which are believed to be key intermediates toward interconversion products. We thus devise a theoretical model that rationalizes experimentally observed phenomenon of disulfides different reactivity toward nonredox transition metal cation Pd2+.