N-Functionalised heterocyclic carbene complexes of silver

N-Functionalised imidazol-2-ylidene carbene complexes of Ag-I have been pre pared by interaction of the corresponding imidazolium salt with Ag2O in dic hloromethane or 1,2-dichloroethane in the presence of molecular sieves or w ith 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 carb ene 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 car bene ligands. In the majority of the structurally characterised complexes t he metal centres adopt linear geometries with M-C(carbene) bond lengths in the range of 207-210 pm characteristic of a single bond.