Pyridine bis(imino) iron and cobalt complexes for ethylene polymerization: influence of the aryl imino substituents
Langue
en
Article de revue
Ce document a été publié dans
European Polymer Journal. 2005, vol. 41, n° 6, p. 1288-1295
Elsevier
Résumé en anglais
In the present paper, the synthesis of new pyridine bis(imine) ligands modified with halogens (Cl, Br, CF3) or alkyl groups (Heptyl, tert-butyl, Phenyl,...) is reported. When coordinated with iron or cobalt dichloride, ...Lire la suite >
In the present paper, the synthesis of new pyridine bis(imine) ligands modified with halogens (Cl, Br, CF3) or alkyl groups (Heptyl, tert-butyl, Phenyl,...) is reported. When coordinated with iron or cobalt dichloride, they yielded complexes which were associated to methylaluminoxane (MAO) to achieve the polymerization of ethylene. It was shown that cobalt catalysts are generally more sensitive to the ligand substitutions than the iron ones. The addition of a chlorine atom on the ligand frame is generally unfavorable. On the contrary, the presence of a bromine atom seems more favorable. Phenyl rings lead to almost completely inactive catalysts, probably because of a too weak coordination to the metal. It was also demonstrated that a mono-substitution of the aryl groups with an electron-withdrawing group (-CF3) is sufficient to yield polymers, whereas, considering the bulkiness of this substituent only, oligomers would have been expected< Réduire
Mots clés en anglais
cobalt
pyridine bis(imine)
ethylene polymerization
iron
Origine
Importé de halUnités de recherche