Sm(eta6-C6Me6)(eta2-AlCl4)3: the first structure of a rare earth complex with a neutral π-ligand

The authors and others have demonstrated before that one of these intercalators, UCl4, can undergo arylation reactions to yield eta6-arene complexes and they have structurally characterized such compounds of U(IV) and U(III). In light of the fact that U arene complexes are the only examples of neutral π-ligands bonded to f-elements, they were wondering whether uranium constitutes a special case and whether an f-orbital contribution was instrumental in the bonding. It was therefore tempting to challenge this synthetic approach with lanthanide metals for which there is no structurally characterized complex with neutral π-ligands on record. They have chosen a known intercalator of graphite and wish to report here on the first arene complex of a rare earth element, Sm(eta6-C6Me6)(AlCl4)3-1.5 toluene