Synthesis, characterization, and activity in ethylene polymerization of silica supported cationic cyclopentadienyl zirconium complexes

Nicolas Millot, Sophie Soignier, Catherine C. Santini*, Anne Baudouin, Jean-Marie Maurice Basset

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

41 Scopus citations

Abstract

Cp*ZrMe 3 reacts with silica pretreated at 800 °C, SiO 2-(800) through two pathways: (a) protolysis of a Zr-Me group by surface silanols and (b) transfer of a methyl group to the surface by opening of strained siloxane bridges, in a relative proportion of ca. 9/1, respectively, affording a well-defined surface species [(≡SiO)ZrCp*(Me) 2 ], 3, but with two different local environments 3a, [(≡SiO)ZrCp*(Me) 2 ][≡Si-O-Si≡], and the other with 3b, (Equation presented) The reaction of the species 3 with B(C 6 F 5 ) 3 is controlled by this local environment and gives three surface species [(≡SiO)ZrCp*(Me)] + [MeB(C 6 F 5 ) 3 ] - [≡Si-O-Si≡], 4a (20%), [(≡SiO)ZrCp*(Me)] + [(Me)B(C 6 F 5 ) 3 ] - [≡Si-Me], 4b (10%), and [(≡SiO) 2 ZrCp*] + [(Me)B(C 6 F 5 ) 3 ] - [≡Si-O-Si≡], 5 (70%). On the contrary, the reaction of Cp*Zr(Me) 3 , Cp 2 Zr(Me) 2 with [≡SiO-B(C 6 F 5 ) 3 ] - [HNEt 2 Ph] + , 6, leads to a unique species [(≡SiO)B(C 6 F 5 ) 3 ] - [Cp*Zr(Me) 2 -NEt 2 Ph] + , 7, and [(≡SiO)ZrCp 2 ] + [(Me)B(C 6 F 5 ) 3 ] - , 9 respectively. The complexes 4 and 7 are active catalysts in ethylene polymerization at room temperature, 93 and 67 kg PE mol Zr 1- atm -1 bar -1 , respectively, indicating that covalently bounded Zr catalyst 4 is slightly more active than the "floating" cationic catalyst 7.

Original languageEnglish (US)
Pages (from-to)9361-9370
Number of pages10
JournalJournal of the American Chemical Society
Volume128
Issue number29
DOIs
StatePublished - Jul 26 2006

ASJC Scopus subject areas

  • Catalysis
  • Chemistry(all)
  • Biochemistry
  • Colloid and Surface Chemistry

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