Syntheses, crystal structures, reactivity, and photochemistry of gold(III) bromides bearing N-heterocyclic carbenes

Dalton Trans. 2011 Oct 14;40(38):9899-910. doi: 10.1039/c1dt11175b. Epub 2011 Aug 30.

Abstract

Gold(I) complexes bearing N-heterocyclic carbenes (NHC) of the type (NHC)AuBr (3a/3b) [NHC = 1-methyl-3-benzylimidazol-2-ylidene (= MeBnIm), and 1,3-dibenzylimidazol-2-ylidene (= Bn(2)Im)] are prepared by transmetallation reactions of (tht)AuBr (tht = tetrahydrothiophene) and (NHC)AgBr (2a/2b). The homoleptic, ionic complexes [(NHC)(2)Au]Br (6a/6b) are synthesized by the reaction with free carbene. Successive oxidation of 3a/3b and 6a/6b with bromine gave the respective (NHC)AuBr(3) (4a/4b) and [(NHC)(2)AuBr(2)]Br (7a/7b) in good overall yields as yellow powders. All complexes were characterized by NMR spectroscopy, mass spectrometry, elemental analysis and single crystal X-ray diffraction. Reactions of the Au(III) complexes towards anionic ligands like carboxylates, phenolates and thiophenolates were investigated and result in a complete or partial reduction to a Au(I) complex. Irradiation of the Au(III) complexes with UV light yield the Au(I) congeners in a clean photo-reaction.

MeSH terms

  • Bromides / chemistry*
  • Coordination Complexes / chemical synthesis*
  • Coordination Complexes / chemistry
  • Crystallography, X-Ray
  • Gold / chemistry*
  • Heterocyclic Compounds / chemistry*
  • Methane / analogs & derivatives*
  • Methane / chemistry
  • Models, Molecular
  • Molecular Structure
  • Photochemistry
  • Stereoisomerism

Substances

  • Bromides
  • Coordination Complexes
  • Heterocyclic Compounds
  • carbene
  • Gold
  • Methane