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)dinickel, (NiCp)(2)(mu-C5H6), and (eta(5)- cyclopentadienyl)(eta(3)-cyclopentenyl)nickel, CpNi(eta(3)-C5H7), are formed in the reaction of nickelocene with methyl-lithium and with 1-phenyl-2-methylpropenyl-lithium. The compound (NiCp)(2)(mu-C5H6) can be only formed as a result of the reduction of the cyclopentadienyl ring bonded to the nickel atom whereas the formation of CpNi(eta(3)-C5H7) can be explained by the further hydrogenation 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 system, space group Pnma, with four molecules per unit cell.