Alkylation of cyclopentadienyl rings in the reactions of nickelocene with organolithium compounds

The reaction of nickelocene with tert-butyllithium has been studied. It was found that unstable species {CpNiC(CH3)(3)}, formed in this reaction, reacted further in two directions: beta-H elimination and homolytic cleavage of Ni-C bond. Hydrogen elimination product formed trinickel cluster (NiCp)(3)CCH(CH3)(2) 1, while t-butyl radical alkylated cyclopentadienyl rings to form several compounds. One of these compounds, {Ni[C5H4C(CH3)(3)]}(2)[C5H5C(CH3)(3)] 3, has been isolated and fully characterised. The compound crystallizes from hexane in a triclinic crystal system and P (1) over bar space group. Corresponding unit cell parameters were determined as a = 7.520(2) Angstrom; b = 13.150(5) Angstrom; c = 13.625(4) Angstrom; alpha = 113.77(3)degrees; beta = 97.42(3)degrees; gamma = 90.02(3)degrees; V = 1220.7(7) Angstrom(3); Z = 2. It is the first example of alkylation of cyclopentadienyl rings bonded to nickel by organolithium compounds. (C) 1999 Elsevier Science S.A. All rights reserved.