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Séminaire Chimie ED459

Controlled isospecific polymerization of α-olefins by dichloro zirconium complexes bearing an [OSSO]-type bis(phenolate) ligand

Prof. Norio Nakata (Department of Chemistry, Graduate School of Science and Engineering, Saitama University, Japan)

publié le , mis à jour le

Le Jeudi 03 Juillet 2014 à 14h
ENSCM, amphithéâtre Gerhardt

Co-authors : Norio Nakata,[a] Tomoyuki Toda,[a] Akihiko Ishii,[a] Tsukasa Matsuo[b]
a. Department of Chemistry, Graduate School of Science and Engineering, Saitama University, Japan
b. RIKEN Advanced Science Institute, Saitama, Japan

[OSSO]-type bis(phenolate)s, in which the two phenoxide frameworks are linked to two donor sulfur atoms in the ortho- or benzyl-positions, have been of great interest as dianionic ancillary tetradentate ligands for Group 4 metal centers.[1] Recently, we reported the development of a new [OSSO]-type bis(phenolate) ligand 1 based on a trans-1,2-cyclooctanediyl platform and syntheses of a variety of dialkyl zirconium complexes 2.[2,3] Upon activation with B(C6F5)3 or (Ph3C)[B(C6F5)4], dibenzyl zirconium complex 2a achieved highly active (>2500 g mmol–1 h–1) and completely isospecific polymerization of 1-hexene.[2] We present here the catalytic behavior of dichloro zirconium complex 3 as a pre-catalyst in the polymerization of α-olefins.

Dichloro zirconium complex 3 was prepared by the reaction of the dilithium salt of ligand 1 with ZrCl4 at −78 °C in 73% yield as colorless crystals. The complex 3 activated by dMAO (dried methylalminoxane) showed an extremely high activity (>18,000 g mmol–1 h–1) toward polymerization of 1-hexene and provided highly isotactic poly(1-hexene) with a narrow polydispersity (Mw = 40,000 g mol−1, PDI = 1.9). Moreover, the polymerization of 4-methyl-1-pentene (4-MP) catalyzed by the 3/dMAO system in toluene at 25−70 °C produced excellently isotactic poly(4-MP)s (Mw = 10,400−17,500 g mol–1, PDI = 1.9−2.2) with good activities (160−500 g mmol–1 h–1). We also describe the catalytic ability for the cyclopolymerization of 1,5-hexadiene with the 3/dMAO system.

References

1. Nakata, N. ; Toda, T. ; Ishii, A. Polym. Chem. 2011, 2, 1597−1610.
2. Ishii, A. ; Toda, T. ; Nakata, N. ; Matsuo, T. J. Am. Chem. Soc. 2009, 131, 13566−13567.
3. Toda, T. ; Nakata, N. ; Matsuo, T. ; Ishii, A. J. Organomet. Chem. 2011, 696, 1258−1261.

Contact local ICGM : Dr. Michel Wong Chi Man (équipe AM2N)

Agenda

séminaire

  • Jeudi 3 juillet 2014 14:00-15:30 -

    Controlled isospecific polymerization of α-olefins by dichloro zirconium complexes bearing an [OSSO]-type bis(phenolate) ligand

    Résumé : Séminaire Chimie ED459 – Norio Nakata

    Lieu : ENSCM, amphi Gerhardt


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