Trinuclear gold clusters supported by cyclic (alkyl)(amino)carbene ligands: mimics for gold heterogeneous catalysts

Abstract

The synthesis of air- and moisture-stable trinuclear mixed-valence gold(I)/gold(0) clusters is described. They promote the catalytic carbonylation of amines under relatively mild conditions. The synthetic route leading to the trinuclear clusters involves a simple ligand exchange from the readily available μ(3)-oxo-[(Ph3 PAu)3O](+) complex. This synthetic method paves the way for the preparation of a variety of mixed-valence gold(I)/gold(0) polynuclear clusters. Moreover, the well-defined nature of the complexes demonstrates that the catalytic process involves a rare example of a definite change of oxidation state of gold from Au(0)2Au(I) to Au(I)3.

Keywords: amine carbonylation; carbenes; gold clusters; heterogeneous catalysis.