PENTABENZYLCYCLOPENTADIENIDES OF LITHIUM

(Pentabenzylcyclopentadienyl)lithium (Li(eta(5)-C(5)Bz(5))) has been p repared by lithiation of pentabenzylcyclopentadiene with tert-butyllit hium in toluene or benzene. This compound, which is the nonisolated st arting material for most of the known pentabenzylcyclopentadienides, h as been characterized by NMR and mass spectroscopy. The molecular stru cture of the benzene adduct of dimeric Li(eta(5)-C(5)Bz(5)) has been d etermined by X-ray diffraction studies. A triple-decker-like structure , (5)-C(5)Bz(5))Li(eta(5)-C(5)Bz(5))Li(eta(2)-C6H6), results. The reac tion of Li(eta(5)-C(5)Bz(5)) with Al(eta(5)-C(5)Me(5)) leads to Al(eta (5)-C(5)Bz(5)) and Li(eta(5)-C(5)Me(5)), with [Li(eta(5)-C(5)Bz(5))(2) ][Al(eta(5)-C(5)Me(5))(2)] as a side product. The molecular structure of the last-named compound consists of the separated sandwich ions [Li (eta(5)-C(5)Bz(5))(2)](-) and [Al(eta(5)-C(5)Me(5))(2)](+).