Cyclopentadienylnickel Clusters

The mechanism of the reaction of nickelocene with methyllithium is complicated and not, as yet, fully explained. The new C-C bond and a number of higher cyclopentadienylnickel clusters are formed in this reaction. The clusters are often unstable and difficult to isolate in a pure state. There is, however, no doubt, that the first step of the reaction is the formation of unstable CpNiCH3. This complex... 

It has been found previously that NiCp2 reacts with phenyllithium or phenyl-magnesium bromide in THF, in the temperature range —40°C - room temperature, to form biphenyl and a mixture of cyclopentadienylnickel clusters. The active dinickel species (NiCp)2) is formed in this reaction as an intermediate (Eqs. (15), (16)). 

Bulk reduction of [NiCp2] in MeCN or thf yields some [Ni(fj3-C5H7)Cp] and uncharacterized products (299, 498). Sodium naphthalide in thf gives a mixture of remarkable polynuclear, cyclopentadienylnickel compounds containing between two and six metal atoms. The octahedral cluster [ NiCp 6] and its monocation are the first to be structurally characterized (519). 

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