Oxidation of Thiol-containing Substrates by the Pentaamminechromatocobalt(III) Complex Ion

Abstract

The reactions of the pentaamminechromatocobalt( III) complex ion with a series of thiols, RSH (where RSH = glutathione, L-cysteine, and DLpenicillamine) have been studied by spectrophotometry at pH > 7, over the range 20°C ≤ T ≤ 34.4°C, with the thiols in excess at ionic strength 0.50 Μ (NaClO4). The reactions occur in two stages; the first is a rapid reaction between reactants leading to formation of outer-sphere adducts, which are facilitated by electrostatic interaction between the Chromate complex and each thiol. For L-cysteine, the equation representing the first stage is