N-Heterocyclic carbenes

The idea of a themed issue dedicated to N-heterocyclic carbenes (NHCs) in transition metal chemistry developed from discussions at a Dalton Transactions Council meeting. A dedicated issue on NHCs seemed timely considering the tremendous growth that the area has recently experienced.

The use of NHCs as ligands in transition metal chemistry over the past decade has been phenomenal. Looking at last year's metrics, a simple Web of Science search reveals that the N-heterocyclic carbene keyword leads to over 700 hits and more than 25 000 citations. Overall, this search spanning the last two decades yielded impressive numbers: more than 4400 hits with nearly 130 000 citations and an h-index of 136! Much of the activity revolves around palladium and ruthenium due to the success stories of these ligands in olefin metathesis and cross coupling catalysis.

This volume presents work in the classics but also emerging areas. The collection of 29 articles gives an overview of the field. The volume opens with a perspective by Gaillard and moves through mechanistic, computational and catalytic contributions going as far in scope as describing the biological activity of gold complexes. The spectrum of applications is quite broad and I hope the reader finds contributions to his/her liking but also in the process of perusing through the excellent papers, becomes exposed to areas that (s)he might not be as familiar with and peak his/her curiosity. The field is one that some may call “mature” but still holds numerous surprises. A large number of the articles describe such surprises and I thank the authors for their fine contributions.

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