13C and 15N NMR studies of the interaction of gold(I) captopril with selenocyanate, selenourea, and thiourea in aqueous solution

Abstract

The interaction of KSe 13C 15N with gold(I)-captopril (Aucap) n in aqueous solution was studied by 13C and 15N NMR spectroscopy. The Se 13C 15N − interacts with (Aucap) n to form an unstable [capAuSe 13C 15N] − species which readily undergoes disproportionation and redox reactions to generate [Au( 13C 15N) 2] −, (cap) 2, Se 0, and Au 0. The approximate second-order rate constant of disproportionation of [capAuSe 13C 15N] − is found to be 0.014 ± 0.001 1 mol −1 h −1. The 13C and 15N chemical shifts and 1J( 77- 13C) and 1J( 13C- 15N) coupling constants for free Se 13C 15N − and [Au( 13C 15N) 2] − species are reported. The interaction of selenourea (SeU) with (Aucap) n resulted in the formation of a [capAuSeU] complex which underwent decomposition and redox reactions to produce (cap) 2, Se 0, and Au 0 species. Thiourea gave rise to a stable [capAuTU] complex which did not undergo redox reaction.