Synthesis of n-heterocyclic salts and their properties

Since the first report by Ofele in 1968, and the first isolation by Arduengo in 1991, N-heterocyclic carbenes (NHCs) have attracted many attentions, especially for its applications in catalytic reactions. In recent years, NHCs are widely used as organocatalysts and ancillary ligands in transitions metal catalyzed reactions. Using these ligands, synthesised complexes have showed high catalytic activity in methathesis, creation of furane, polymerization, hydrosilylation, hydrogenation, and coupling reactions. NHCs are usually considered as analogues of phosphine ligands because of their good ? -donating but very weak ? -accepting ability. Generally, NHCs-metal complexes have higher stability toward heat, moisture, and oxygen than phosphine metal-based complexes, which makes them quite attractive as phosphine surrogates.