REDUCTION OF THE GOLD(III) COMPLEX ION, [AUCl3OH]-, BY N-METHYLTHIOUREA, N, N’–DIMETHYLTHIOUREA AND N, N’- DIETHYLTHIOUREA IN AQUEOUS ACID: KINETIC, THERMODYNAMIC AND MECHANISTIC STUDIES

Abstract

The kinetic, thermodynamic and mechanistic studies of the reduction of the gold(III) complex ion, [AuCl3OH]- by N-methylthiourea (MTU), N, N’- dimethylthiourea (DMTU) and N, N’– diethylthiourea (DETU) were studied spectrophotometrically in aqueous acid. Stoichiometry revealed that two moles of N-methylthiourea, N,N’–dimethylthiourea and N,N’- diethylthiourea each were oxidised by one mole of gold(III) ion. The rate showed a first order dependence on [AuCl3OH]- and half-order on [reductants] with one and half order overall. The reactions were biphasic revealing an initial substitution step and a final electron transfer phase. Addition of acid within the range 5.0 x10-4 - 1.0 x 10-2 mol dm-3 led to decrease in.......