Reaction of nickelocene with methyllithium in the presence of 2-butyne

Reaction of nickelocene with methyllithium in the presence of 2-butyne at the molar ratio of reactants 1:1:1 leads to the formation of several organinickel compounds. Five of these products were isolated and identified. A novel, 49-electron tri(cyclopentadienylnickel) nickel cluster (CpNi)3·(CH3CCCH3) (5) was fully characterized by spectroscopic and X-ray measurements. Alkyne ligand is bonded to three nickel atoms via two σ and one π bonds (2σ+π bond system). Compound 5 crystallizes from hexane in a monoclinic crystal system and P21/n space group. Corresponding unit cell parameters were determined as a=9.015(2) Å; b=14.608(3) Å; c=13.983(3) Å; β=108.47(3)°; V=1746.6(6) Å3; Z=4.