Chelating Bis(N-Heterocyclic Carbene) Palladium-Catalyzed Reactions

N-Heterocyclic carbenes (NHCs) have been widely employed in the construction of various metal complexes and applied in the field of catalysis. In this review, a series of palladium complexes comprising chelating bis(NHC) donors (Pd-bis(NHC) complexes) are outlined according to their application in homogeneous catalysis. Examples of metal-organic frameworks containing Pd-bis(NHC) moieties are briefly discussed, in terms of their use in heterogeneous catalysis. The catalytic applications of Pd-bis(NHC) complexes (or moieties in heterogeneous catalysts) are mainly focused on the Mizoroki-Heck, Suzuki-Miyaura, and Sonogashira coupling reactions. Another 14 types of reactions are also summarized beyond these three types of reactions.