B. Temme et al., BORON-INDUCED FORMATION OF A METHYLENECYCLOPROPENE UNIT IN THE BIS(CYCLOPENTADIENYL)ZIRCONIUM COORDINATION SPHERE, Journal of the Chemical Society, Chemical Communications, (14), 1994, pp. 1713-1714
Bis(propynyl)zirconocene 1 undergoes alkynyl ligand coupling upon trea
tment with B(C6F5)(3); the resulting (C5H5)(2)Zr(mu-2,4-hexadiyne)BAr3
betaine 2 reacts with benzonitrile to give a Zr/B-bridging methylenec
yclopropene derivative 5 that is formed via intramolecular alkyne inse
rtion into a Zr-C(sp(2)) sigma bond; complex 5 was characterized by si
ngle-crystal X-ray diffraction.