Clusters containing carbene ligands. The formation of a carbene ligand by carbon-hydrogen activation of a .pi.-complexed iminium ligand

Abstract

Recently, there has been a flurry of interest in the nature of the activation of olefinic CH bonds by metal complexes. Studies have shown that the barriers to the activation of CH bonds of ..pi..-complexed olefins by mononuclear metal complexes are very large. Indeed, evidence has been presented which demonstrates that olefinic CH activation by certain mononuclear metal complexes occurs without precoordination of the olefin. By contrast olefininc CH activation by polynuclear metal complexes and on surfaces is a relatively facile process. In these cases, it is believed that the activation step is a two-center process in which the olefin is coordinated to one metal atom and the CH cleavage takes place by interaction at a vacant coordination site on a neighboring metal atom. Iminium ions, H/sub 2/C=NR/sub 2//sup +/, are isoelectronic to olefins, and they are known to form ..pi..-bonded complexes analogous to ..pi..-olefin complexes. In this communication is described the first example of a C-H activation of a ..pi..-complexed iminium ion and its conversion into a dialkylaminocarbene ligand.