Preparation and application of N-heterocyclic carbene complexes of Ag(I)

The current status (up to 31 July 2006) of Ag(I)-NHCs (NHC = N-heterocyclic carbene) is presented with various NHC systems ranging from five membered to seven membered rings, including imidazolium, benzimidazolium, imidazolinium, triazolium, pyrimidinium, pyrazolium, seven-membered amidinium, and naphthimidazolium moieties, etc. It is our intention to provide an updated, and comprehensive review on the subject of Ag(l)-NHCs, which may further accelerate work on this topic. The main features of this review are to focus on (a) the ease and limitations in the synthesis of Ag(l)-NHCs, (b) the parameters influencing the solid state structures of Ag(l)-NHCs, and (c) the efficacy of Ag(l)-NHCs in transmetallation reactions. In particular, we would like to evaluate the widely adopted Ag2O technique in the preparation of Ag(I)-NHCs and the subsequent NHC transfer reactions, to afford other metal-NHCs. (c) 2006 Elsevier B.V. All rights reserved.