Notes. Exchange kinetics of gold(I) phosphine complexes by nuclear magnetic resonance line shape analysis

Abstract

The ³¹P-{¹H} n.m.r. spectra of [NEt₄][AuBr₂] with various amounts of the ligands PPhMe₂ or PBuⁿ₃ were studied at different ratios in CD₂Cl₂ solutions. The solutions show the presence of species having one, two, and three co-ordinated phosphine ligands (four in the case of PBuⁿ₃), and these species exchange with one another at elevated temperatures. The entropies of activation (ΔS^‡) for these processes are negative and the mechanism of exchange is thus associative in all cases.