Fluorinated N-Heterocyclic carbene complexes. Applications in catalysis

N-heterocyclic carbenes (NHC) are one of the most versatile type of ligands described up to date, this being in part due to the facile modulation of their electronic and steric properties. Hence, they can coordinate to practically any transition metal producing very strong C-M bonds, affording excellent scaffolds for the design of new catalysts and advanced materials. In addition, fluorinated compounds have found a plethora of applications in different areas of chemistry, from materials to pharmaceuticals, allowing the fine tuning of their electronic properties, and NHC and their corresponding complexes have not escaped this fashion. However, this chemistry has not been widely explored nor reviewed, this being particularly true in the case of their application as catalysts (other applications in medicinal chemistry and photophysical properties are out of the scope of this paper) and thus, this review summarizes the synthetic routes and potential effect of fluorine or fluorinated substituents on NHC transition metal complexes and their applications in catalysis.