Facile synthesis of silver(I)-carbene complexes. Useful carbene transfer agents

[Ag(Et-2-Bimy)(2)][AgBr2] (1; Et-2-Bimy = diethylbenzimidazol-2-ylidene) was obtained readily from the reaction of [Et-2-BimyH]Br with Ag2O. Compound 2, (Ag(Et-2-Bimy)(2)]PF6, was prepared by the reaction of [Et-2-Bimy]PF6 with Ag2O under basic phase transfer catalysis conditions. Both compounds 1 and 2 are good carbene transfer agents. Thus, Pd(Et-2-Bimy)(2)Cl-2, Au(Et-2-Bimy)Br, and [Au(Et-2-Bimy)(2)]PF6 were obtained in high yields using 1 and 2 as carbene sources. The byproduct AgBr or AgCl can be reused to generate 1 under basic phase transfer catalysis conditions. The crystal structure of compound 1 revealed that linear [Ag(Et-2-Bimy)(2)](+) and [AgBr2](-) groups were associated through a short Ag-I-Ag-I contact (2.956 Angstrom). FAB/mass spectrometry and molar conductivity measurements indicate the existence of ligand-unsupported Ag-I-Ag-I interactions in the gas phase and acetonitrile solution. C-13 NMR studies suggest that the two Bimy ligands in 1 are fluxional in solution.