Bis[(amidomethyl)pyridine] Zirconium(IV) Complexes: Synthesis, Characterization, and Activity as Olefin Polymerization Catalysts

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• 作者：Liana Annunziata ; Daniela Pappalardo ; Consiglia Tedesco ; Claudio Pellecchia
• 刊名：Organometallics
• 出版年：2009
• 出版时间：February 9, 2009
• 年：2009
• 卷：28
• 期：3
• 页码：688-697
• 全文大小：216K
• 年卷期：v.28,no.3(February 9, 2009)
• ISSN：1520-6041

文摘

This contribution describes the synthesis, characterization, and olefin polymerization reactivity of bis(chelate)zirconium complexes bearing (amidomethyl)pyridine ligands [(6-X-C₅H₃N)CH₂NC₆F₅, X = CH₃ (Lig¹H), Br (Lig²H), H (Lig³H)]. Metathesis reaction, alkane elimination, and amine elimination provided routes to compounds (Lig¹)₂ZrCl₂ (1), (Lig¹)₂ZrBz₂ (4; Bz = CH₂C₆H₅), and (Lig²)₂Zr(NMe₂)₂ (5). Attempts to prepare (Lig¹)₂Zr(NMe₂)₂ in a reaction between Zr(NMe₂)₄ and Lig¹H led instead to compound (Lig¹)(Lig¹*)ZrF(NMe₂) (2), in which one dimethylamino group had been exchanged with one ortho fluoride on the perfluorophenyl ring of the ligand via an aromatic nucleophilic substitution reaction. Halide displacement reaction performed on compound 2 afforded the dichloride compound (Lig¹)(Lig¹*)ZrCl₂ (3). Reaction between Zr(NMe₂)₄ and Lig³H provided a mixture of (Lig³)₂Zr(NMe₂)₂ and (Lig³)(Lig³*)ZrF(NMe₂), the latter being analogous to 2. X-ray crystallographic analysis showed for compound 1 a distorted octahedral geometry with C₁ symmetry and for compound 2 a 7-coordinate species. Variable-temperature NMR studies established for compound 1 an inversion of metal configuration through dynamic interchange of the all-cis enantiomers. Fluxional behaviors in solution were also observed for compounds 2, 3, and 4. Treatment of complexes with AlⁱBu₂H and methylalumoxane (MAO) yields active, multisite ethylene and propylene polymerization catalysts.