Synthetic Routes to Late Transition Metal–NHC Complexes

Transition metal complexes bearing N-heterocyclic carbene ligands (NHCs) have gained a place of crucial importance in numerous areas of research such as medicinal chemistry, material sciences, and homogeneous/heterogeneous catalysis. In the present review, an updated overview of the main synthetic routes used for the preparation of this broad class of compounds along with their main applications are reported. Particular attention will be paid to the synthesis of late transition metal–NHC complexes using weak bases, eco-friendly solvents, and mild operating conditions. This simple synthetic approach, also known as the ‘weak base route’, represents a recent development with yet unrealized potential.