Stereoselectivity in the 1,2-polymerization of 1,3-dienes with cobalt phosphine complexes based catalysts (Contributo in atti di convegno)

Type
Label
  • Stereoselectivity in the 1,2-polymerization of 1,3-dienes with cobalt phosphine complexes based catalysts (Contributo in atti di convegno) (literal)
Anno
  • 2008-01-01T00:00:00+01:00 (literal)
Alternative label
  • Ricci, G.; Boglia, A.; Leone, G.; Boccia, A. C.; Zetta, L.; Forni, A. (2008)
    Stereoselectivity in the 1,2-polymerization of 1,3-dienes with cobalt phosphine complexes based catalysts
    in International Workshop on Olefin Polymerization Kinetics, Tokyo (Japan)
    (literal)
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  • Ricci, G.; Boglia, A.; Leone, G.; Boccia, A. C.; Zetta, L.; Forni, A. (literal)
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  • It has been reported that the system CoBr2(PPh3)2-MAO gives from butadiene a polymer with a mixed cis-1,4/1,2 structure, while a highly cis-1,4 polybutadiene is obtained with CoCl2-MAO, suggesting that the presence of a ligand on the cobalt atom may strongly influence the polymerization stereospecificity. To check this indication we have synthesized and fully characterized various cobalt complexes of the type CoCl2(PRPh2)2 (R =methyl, ethyl, npropyl, ipropyl, cyclohexyl); for some of them the crystalline molecular structure was also determined. In combination with methylaluminoxane, they were found to be extremely active and stereospefic in the polymerization of butadiene, giving essentially 1,2 polymers, iso-or syndiotactic depending on the type of ligand bonded to the metal2. The formation of polymers having different tacticity, depending on the catalyst structure, was interpreted according to the diene polymerization mechanism proposed several years ago by Porri3, by admitting that the type of ligand may affect the reciprocal orientation (exo-exo or exo-endo) of the allyl group and of the diene monomer coordinated to the metal, thus determining the polymerization stereoselectivity. (literal)
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  • G. Ricci – Ismac-Milano, A. Boglia – Ismac-Milano, G. Leone –Ismac-Milano, A. C. Boccia – Ismac-Milano, L. Zetta – Ismac-Milano, A. Forni – CNR-ISTM-Milano. (literal)
Titolo
  • Stereoselectivity in the 1,2-polymerization of 1,3-dienes with cobalt phosphine complexes based catalysts (literal)
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