Synthesis and characterization of Au(I) and Au(III) complexes containing N-heterocyclic ligands derived from amino acids

A series of [Au(NHC)2] (1a–4a) complexes supported by NHC ligands derived from glycine, alanine, methionine and phenylalanine (1–4 respectively) were prepared via a direct transmetalation reaction of their respective silver complexes. The Au complexes were characterized by ESI-MS and NMR spectroscopy in solution. These compounds exhibit instability when the solvent is removed; they displayed a strong tendency to form colored solutions in the order 4a > 3a > 2a > 1a, which is associated with gold nanoparticles. 1a and 2a undergo oxidative addition of elemental bromine, yielding [Au(NHC)2Br2] (1b) for 1a and a mixture of [Au(NHC)2Br2] (2b) and [Au(NHC)Br3] (2c) for 2a. 2b and 2c were characterized by single crystal X-ray diffraction.

Graphical abstractA family of water soluble gold(I) complexes with NHC carbene ligands derived from amino acids were prepared via the direct transmetalation reaction of the respective silver NHC complexes. The oxidative addition of Br2 to Au(I)-NHC complexes was studied and the crystal structure of [AuBr3(NHC)] compound derived from alanine is presented.Figure optionsDownload full-size imageDownload as PowerPoint slide