Efficient Synthesis of Bulky N-Heterocyclic Carbene Ligands for Coinage Metal Complexes

A facile and efficient route to synthesize sterically bulky N-heterocyclic carbenes with high percent buried volumes has been developed. The method involves three steps from commercial reagents and produced the NHC precursors with approximately 40% overall yield without column chromatography. The free carbenes were isolated as confirmed by X-ray crystallography and C-13 NMR peak at 213 ppm corresponding to the carbene carbons. The Cu(I), Ag(I), and Au(I) chloride complexes supported by the NHC ligands were successfully synthesized and fully characterized including X-ray crystallography. (C) 2016 Elsevier B.V. All rights reserved.1174Nsciescopu