N-Heterocyclic Carbenes Capped Metal Nanoparticles: An Overview of Their Catalytic Scope

Abstract

N-Heterocyclic carbenes (NHCs) have become the most celebrated ligands in various fields of chemistry due to their unique electronic properties. (1−5) Since the first stable N-heterocyclic carbene was isolated, many other variations of stable carbenes have also been reported. (6) The cyclic five-membered NHC possesses a formally divalent carbon center, stabilized by σ-electron-withdrawing and π-electron-donating nitrogen atoms next to the carbene carbon (Figure 1). Owing to the presence of a lone pair of electrons and an empty p-orbital, these NHCs have proven to be potential ligands for stabilizing a wide range of reactive main-group and transition-metal species and many applications in the fields of catalysis and materials chemistry continue to emerge. (7−9)