Synthesis And Coordination Chemistry Of Silver(I), Gold(I) And Gold(Iii) Complexes With Picoline-Functionalized Benzimidazolin-2-Ylidene Ligands

The reactions of N-alkyl-N'-picolyl-benzimidazolium bromides or N,N'-dipicolyl-benzimidazolium bromide with silver oxide yielded the silver dicarbene complexes of the type [Ag(NHC)(2)][AgBr2] 1-4 (NHC = picoline-functionalized benzimidazolin-2-ylidene). The silver complexes 1-4 have been used in carbene transfer reactions to yield the gold(I) complexes of the type [AuCl(NHC)] 5-8 in good yields. A halide exchange at the metal center of complexes 5-8 with lithium bromide yielded the gold bromide complexes 9-12. Finally, the oxidation of the gold(I) centers in complexes 9-12 with elemental bromine gave the gold(III) complexes of the type [AuBr3(NHC)] 13-16. Molecular structures of selected Au(I) and Au(III) complexes have been determined by X-ray diffraction studies.