N-Functionalised heterocyclic carbene complexes of silver

Abstract

N-Functionalised imidazol-2-ylidene carbene complexes of Ag^I have been prepared by interaction of the corresponding imidazolium salt with Ag₂O in dichloromethane or 1,2-dichloroethane in the presence of molecular sieves or with Ag₂CO₃ in 1,2-dichloroethane. In an analogous way disilver(I) complexes of o-phenylenedimethylenebis(imidazol-2-ylidene) have been obtained. Their structures, as determined by X-ray crystallography, indicate that the carbene ligand acts as monodentate from the carbene end or as a bridge between two different metal atoms. In one case the silver is coordinated by two carbene ligands. In the majority of the structurally characterised complexes the metal centres adopt linear geometries with M–C(carbene) bond lengths in the range of 207–210 pm characteristic of a single bond.