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Self‐Immobilizing Precatalysts: Norbornene‐Bridged Zirconium ansa‐ Metallocenes
Author(s) -
Polo Eleonora,
Forlini Fabrizio,
Bertolasi Valerio,
Boccia Antonella Caterina,
Sacchi Maria Carmela
Publication year - 2008
Publication title -
advanced synthesis and catalysis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.541
H-Index - 155
eISSN - 1615-4169
pISSN - 1615-4150
DOI - 10.1002/adsc.200800168
Subject(s) - chemistry , metallocene , norbornene , polymerization , catalysis , polymer chemistry , zirconium , degree of unsaturation , ethylene , polymer , organic chemistry
We report here the synthesis of new tethered biscyclopentadienyl and bisindenyl zirconocenes, bearing one unsaturation on the interannular bridge, and their use as self‐immobilizing catalysts. They proved to be active catalysts towards ethylene polymerization in solution, with activities comparable to those displayed by commercial rac ‐Et(Ind) 2 ZrCl 2 . When tested as self‐polymerization catalysts under suitable experimental conditions, they gave colored precipitates that, once reactivated with MAO, were significantly active in ethylene polymerization, although lower than those of the corresponding catalytic systems in solution. The molecular weights of the produced polymers were similar to those obtained with the same catalysts in solution, but their distribution resulted to be broader, with values typical of heterogeneous catalytic systems. From 13 C NMR studies we had the first spectroscopic evidence of the actual incorporation of a metallocene of this type into a polymeric chain.