Sm(eta/sup 6/-C/sub 6/Me/sub 6/)(eta/sup 2/-AlCl/sub 4/)/sub 3/: the first structure of a rare earth complex with a neutral. pi. -ligand

The authors and others have demonstrated before that one of these intercalators, UCl/sub 4/, can undergo arylation reactions to yield eta/sup 6/-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 ..pi..-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 ..pi..-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(eta/sup 6/-C/sub 6/Me/sub 6/)(AlCl/sub 4/)/sub 3/-1.5 toluene.