REACTIONS OF NICKELOCENE WITH METHYL-LITHIUM, ETHYL-LITHIUM AND VINYL-LITHIUM COMPOUNDS - HYDROGEN ELIMINATION AND CYCLOPENTADIENYL RING HYDROGENATION

It has been shown that bis(cyclopentadienyl)(mu-cyclopentadiene)dinick el, (NiCp)(2)(mu-C5H6), and (eta(5)- cyclopentadienyl)(eta(3)-cyclopen tenyl)nickel, CpNi(eta(3)-C5H7), are formed in the reaction of nickelo cene with methyl-lithium and with 1-phenyl-2-methylpropenyl-lithium. T he compound (NiCp)(2)(mu-C5H6) can be only formed as a result of the r eduction of the cyclopentadienyl ring bonded to the nickel atom wherea s the formation of CpNi(eta(3)-C5H7) can be explained by the further h ydrogenation of cyclopentadiene formed in the earlier reaction steps. (NiCp)(2)(mu-C5H6) has been fully characterised spectrometrically and its X-ray structure determined. It crystallises in the orthorhombic sy stem, space group Pnma, with four molecules per unit cell.