Half-sandwich β-diketonato complexes of zirconium and their application as catalysts to ethylene pol

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The bis(β-diketonato) Zr complexes CpZr(acac)2Cl (acac = acetylacetonato) (1) and Cp*Zr(acac)2Cl (2) can be synthesized by the reac-tion of Cp′ZrCl3(Cp′ = Cp or Cp*) with 2 equiv of lith-ium acetylacetonate. CpZr(acac)2Cl (1) can be quan-titatively prepared by treatment of Cp2ZrCl2 with ex-cess acetylacetone. The tris(β-diketonato) Zr com-plex CpZr(tfac)3 (tfac = trisfluoroacetylacetonato) (3) has been prepared by treatment of CpZrCl3 with so-dium trisfluoroacetylacetonate. The replacement of both chlorine atoms and one Cp group from zir-conocene dichloride by nonfluorinated diketone,acetylacetone,readily occurs at room temperature in triethylamine medium,offering the tris(β-diketonato) Zr complex CpZr(acac)3 (4). The complexes were characterized by 1H NMR spectroscopic methods. In addition,the molecular structures of complexes 3 and 4 have been determined by X-ray diffraction methods. When activated by excess methylaluminoxane (MAO),these complexes were active for ethylene polymerization,offering polyethylenes with high mo-lecular weights and narrow molecular weight distribu-tions. Complex 4 showed a very high ethylene po-lymerization activity of up to 7100 kg PE/mol Zr·h at 5 atm. Complexes 1 and 2 were also active for ethyl-ene/1-hexene copolymerization. The bis (β-diketonato) Zr complexes CpZr (acac) 2Cl (acac = acetylacetonato) (1) and Cp * Zr (acac) 2Cl (2) can be synthesized by the reac tion of Cp’ZrCl3 CpZr (acac) 2Cl (1) can be quan-titatively prepared by treatment of Cp2ZrCl2 with ex-cess acetylacetone. The tris (β-diketonato) Zr com-plex CpZr tfac) 3 (tfac = trisfluoroacetylacetonato) (3) has been prepared by treatment of CpZrCl3 with so-dium trisfluoroacetylacetonate. The replacement of both chlorine atoms and one Cp group from zir-conocene dichloride by non-fluorinated diketone, acetylacetone, in triethylamine medium, offering the tris (β-diketonato) Zr complex CpZr (acac) 3 (4). The complexes were characterized by 1H NMR spectroscopic methods. ray diffraction methods. When activated by excess methylaluminoxane (MAO), these complexes were active for ethylene poly Complex 4 showed a very high ethylene po-lymerization activity of up to 7100 kg PE / mol Zr · h at 5 atm. Complexes 1 and 2 were also active for ethyl-ene / 1-hexene copolymerization.
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