Regarding the Stability of d0 Monocyclopentadienyl Zirconium Acetamidinate Complexes Bearing Alkyl Substituents with β-Hydrogens
- 1 May 2002
- journal article
- research article
- Published by American Chemical Society (ACS) in Journal of the American Chemical Society
- Vol. 124 (21) , 5932-5933
- https://doi.org/10.1021/ja017294o
Abstract
The monocyclopentadienyl zirconium acetamidinate complexes, (η5-C5Me5)Zr[N(R 1)C(Me)N(R 2)]R 3R 4 (1−8), have been shown to be remarkably resistant to β-hydrogen eliminations/abstractions, including the tert-butyl derivative, 3 (R1 = R2 = Cy, R3 = t-Bu, R4 = Cl), which resists both decomposition and isomerization in solution to temperatures of at least 100 °C. Further, two striking examples of an apparent preference for alternative hydrogen-atom abstractions in which complexes 1 and 7/8 that bear isomeric dibutyl substituents are transformed at elevated temperatures to complexes 9 and 10/11 that contain the isomeric butadiene and trimethylenemethane (TMM) C4 fragments, respectively, are presented. These results serve to not only introduce a new ligand environment for zirconium in which β-hydrogen elimination/abstraction processes are substantially retarded, but they further document the availability of alternative low-energy hydrogen abstraction pathways for group 4 alkyl complexes.Keywords
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