The peculiar behavior of a diphosphirenium salt towards sodium η5-cyclopentadienyl(dicarbonyl)ferrate

A novel, 65-electron tetranuclear nickel cluster of the formula Cp3Ni4(CH3CCCH3)3 (6) was isolated and identified as the product of the reaction of nickelocene with methyllithium in the presence of 2-butyne at the molar ratio of reactants 1:1:1. The compound was fully characterised by spectroscopic and X-ray measurements. It crystallises from hexane in an orthorhombic crystal system and space group Pbcn. Corresponding unit cell parameters were determined as a=26.438(5), b=11.219(2), c=16.328(3) Å; α=β=γ=90°; V=4843(2) Å3; Z=8.