title: Regarding the stability of d(0) monocyclopentadienyl zirconium acetamidinate complexes bearing alkyl substituents with beta-hydrogens.
abstract: The monocyclopentadienyl zirconium acetamidinate complexes, (eta(5)-C(5)Me(5))Zr[N(R(1))C(Me)N(R(2))]R(3)R(4) (1-8), have been shown to be remarkably resistant to beta-hydrogen eliminations/abstractions, including the tert-butyl derivative, 3 (R(1) = R(2) = Cy, R(3) = t-Bu, R(4) = Cl), which resists both decomposition and isomerization in solution to temperatures of at least 100 degrees 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) C(4) fragments, respectively, are presented. These results serve to not only introduce a new ligand environment for zirconium in which beta-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.
authors.affiliation: Department of Chemistry and Biochemistry, University of Maryland, College Park, Maryland 20742, USA.
authors.forename: Richard J
authors.initials: RJ
authors.lastname: Keaton
authors.forename: Lisa A
authors.initials: LA
authors.lastname: Koterwas
authors.forename: James C
authors.initials: JC
authors.lastname: Fettinger
authors.forename: Lawrence R
authors.initials: LR
authors.lastname: Sita