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, reac ted 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 fo rm several compounds. One of these compounds, {Ni[C5H4C(CH3)(3)]}(2)[C5H5C( CH3)(3)] 3, has been isolated and fully characterised. The compound crystal lizes from hexane in a triclinic crystal system and P (1) over bar space gr oup. Corresponding unit cell parameters were determined as a = 7.520(2) Ang strom; b = 13.150(5) Angstrom; c = 13.625(4) Angstrom; alpha = 113.77(3)deg rees; beta = 97.42(3)degrees; gamma = 90.02(3)degrees; V = 1220.7(7) Angstr om(3); Z = 2. It is the first example of alkylation of cyclopentadienyl rin gs bonded to nickel by organolithium compounds. (C) 1999 Elsevier Science S .A. All rights reserved.