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Methylalumoxane (MAO)‐Derived MeMAO − Anions in Zirconocene‐Based Polymerization Catalyst Systems – A UV‐Vis Spectroscopic Study
Author(s) -
Wieser Ulrich,
Schaper Frank,
Brintzinger HansHerbert
Publication year - 2006
Publication title -
macromolecular symposia
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.257
H-Index - 76
eISSN - 1521-3900
pISSN - 1022-1360
DOI - 10.1002/masy.200690068
Subject(s) - catalysis , ion , olefin fiber , polymerization , olefin polymerization , metallocene , chemistry , polymer chemistry , medicinal chemistry , crystallography , organic chemistry , polymer
Reaction of Me 2 Si(Ind) 2 ZrCl 2 with excess methylalumoxane (MAO) gives rise to ion pairs containing zirconocenium cations of the type [Me 2 Si(Ind) 2 ZrMe] + in contact with two types of anions, MeMAO A − and MeMAO B − , which differ in their coordinative strengths: More strongly coherent contact‐ion pairs [Me 2 Si(Ind) 2 ZrMe +.. MeMAO B − ] are converted by a sufficiently high excess of MAO to more easily separable contact‐ion pairs [Me 2 Si(Ind) 2 ZrMe +.. MeMAO A − ], which react with AlMe 3 to form the outer‐sphere ion pairs [Me 2 Si(Ind) 2 Zr(µ‐Me) 2 AlMe 2 ] + MeMAO A − , and are likely to be required also for the formation of the olefin‐containing reaction complexes responsible for catalytic activity.