Question

What are NHCs and how do they differ from "normal" carbenes?(NHCs is N-heterocyclic carbenes)

Answer 1

N-Heterocyclic carbenes (NHCs) are a specific form of this class of compound, where the carbene is located on an N-heterocyclic scaffold. While these species were initially not widely applied in chemistry, they have now been employed in a broad range of fields, including organocatalysis and organometallic chemistry Hundreds of different NHCs are known in the literature, and much has been learned about their properties and reactivity. Various experimental and theoretical techniques have been applied toward this aim, including density functional theory (DFT) studies, which have allowed an insight into the bonding and orbital arrangements in NHCs. This chapter details the discovery and isolation of stable NHCs, the characterization of the electronic nature of this species, the factors that render them stable, and the nature of their bonding to metal centers.

Normal carbenes are very reactive short lived molecules that cannot be isolated d are usually studied by observing the reaction that undergo.NHC ar usually reactive d quite stable .in many cases they are thermodynamically stable