191599-91-4Relevant academic research and scientific papers
Formation, structure, and dynamic behavior of a novel dinuclear cationic μ-2,4-hexadiyne bis(zirconocene) complex
Ahlers, Wolfgang,Temme, Bodo,Erker, Gerhard,Fr?hlich, Roland,Zippel, Frank
, p. 1440 - 1444 (1997)
Bis(propynyl)zirconocene (1b) reacts with 0.5 molar equiv of trityl tetraphenylborate by a propynyl group transfer to form Ph3CC≡CCH3 and Cp2ZrC≡CCH3+. The in-situ-generated (propynyl)zirconocene cation is not stable under the reaction conditions but instantaneously reacts with the neutral starting material 1b to form the [(μ-C≡CCH3)(μ-CH3C≡CC≡CCH 3)-(ZrCp2)2+][BPh4 -] salt, 9. Complex 9 was characterized by an X-ray crystal structure analysis. It contains an unsymmetrically bridging hexadiyne ligand and exhibits a planar-tetracoordinate carbon center that is stabilized by a three-center two-electron interaction with the two adjacent zirconocene moieties. In solution, complex 9 exhibits dynamic NMR spectra that indicate a symmetrizing exchange of the bonding situations between the two ends of the μ-hexadiyne ligand. The Gibbs activation energy of the automerization reaction of 9 is ΔG?(190 K) ≈ 9.5 kcal mol-1.
