N-Heterocyclic Carbene Complexes of Nickel

The impact of N-heterocyclic carbene (NHC) ligands across the Periodic Table in the last twenty years can be compared to that of classical donor ligands (in particular with P-donors) since the sixties. Nickel has established itself as one of the most popular metals for the application of the NHC ligand paradigm. The interest and topicality of the Ni–NHC organometallic chemistry have been amplified by the current renaissance of the chemistry of 3d metals in catalysis, stemming from its sustainability potential. These trends have been going along with better understanding and advancements of fundamental nature, for example in the areas of ligand design, metal–ligand bonding and metal coordination geometries, fundamental reactivity, electrochemical and magnetic properties, and catalyst development. This chapter will give a comprehensive account of the nickel NHC organometallic chemistry with emphasis on milestones and recent developments. It is constructed on the framework of a recently published comprehensive review by the same authors (Chem. Rev. 2019, 119, 3730 − 3961) and provides a more detailed and up-to-date coverage of the literature (until the end of 2020).