Effects of ligands on the gold (III)-promoted hydrolysis of (N-cyclohexyl)thiobenzamide

Abstract

A study is reported of the kinetics and mechanisms of the hydrolyses in aqueous solution at low pH of (N-cyclohexyl)thiobenzamide promoted by the ions [Au(dien)Cl]²⁺(1), [Au(dien-H)Cl]⁺(2), [Au(NH₃)₄]³⁺(3), and [Au(phen)Cl₂]⁺(4). Ions (1)–(3) employ mechanisms involving the relatively rapid displacement of Cl (or NH₃) by the S-amide, followed by slow hydrolysis steps; with (4) the slow substitution of the S-amide at gold probably controls the rate. The relative reactivities of the gold(III) species as promoters are given and the effects of changes in pH and in ambient chloride ion concentration on the reaction mechanisms are described.