Dinuclear N-heterocyclic carbene copper(I) complexes

Copper(I) species exhibit various coordination modes as a function of surrounding ligands. Complexes bearing N-heterocyclic carbenes as ligands are usually monomeric species with the copper adopting a linear geometry. Contrarily to the parent phosphine complexes, in which the presence of species of higher nuclearity is well established, fewer examples of such copper(I)–NHC species are reported and, interestingly, their number is growing. Moreover, these are no longer a mere curiosity from a coordination perspective since they have been shown successful in catalysis. The aim of this review is to present a summary of the synthesis and structural properties of dinuclear copper(I)–NHC complexes. It is our hope that by centralizing all information available on such species, future efforts aimed at exploiting their full potential can be facilitated.