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-C<sub>5sub>H<sub>3sub>N)CH<sub>2sub>NC<sub>6sub>F<sub>5sub>, X = CH<sub>3sub> (Lig<sup>1sup>H), Br (Lig<sup>2sup>H), H (Lig<sup>3sup>H)]. Metathesis reaction, alkane elimination, and amine elimination provided routes to compounds (Lig<sup>1sup>)<sub>2sub>ZrCl<sub>2sub> (1), (Lig<sup>1sup>)<sub>2sub>ZrBz<sub>2sub> (4; Bz = CH<sub>2sub>C<sub>6sub>H<sub>5sub>), and (Lig<sup>2sup>)<sub>2sub>Zr(NMe<sub>2sub>)<sub>2sub> (5). Attempts to prepare (Lig<sup>1sup>)<sub>2sub>Zr(NMe<sub>2sub>)<sub>2sub> in a reaction between Zr(NMe<sub>2sub>)<sub>4sub> and Lig<sup>1sup>H led instead to compound (Lig<sup>1sup>)(Lig<sup>1sup>*)ZrF(NMe<sub>2sub>) (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 (Lig<sup>1sup>)(Lig<sup>1sup>*)ZrCl<sub>2sub> (3). Reaction between Zr(NMe<sub>2sub>)<sub>4sub> and Lig<sup>3sup>H provided a mixture of (Lig<sup>3sup>)<sub>2sub>Zr(NMe<sub>2sub>)<sub>2sub> and (Lig<sup>3sup>)(Lig<sup>3sup>*)ZrF(NMe<sub>2sub>), the latter being analogous to 2. X-ray crystallographic analysis showed for compound 1 a distorted octahedral geometry with C<sub>1sub> 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 Al<sup>isup>Bu<sub>2sub>H and methylalumoxane (MAO) yields active, multisite ethylene and propylene polymerization catalysts.