Determination of the catalytic active species in the polymerization of propylene by titanium benzamidinate complexes

Victoria Volkis, Anatolii Lisovskii, Boris Tumanskii, Michael Shuster, Moris S. Eisen*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

46 Scopus citations

Abstract

The catalytic behavior of the monomeric titanium bis(benzamidinate) [η-C6H5-C(NSiMe3)2] 2TiCl2 (1), the dimeric titanium mono(benzamidinate) {[η-C6H5-C(NSiMe3)2]TiCl 3]}2 (2), and the monomeric titanium mono(benzamidinate) complex η-C6H5-C(NSiMe3) 2]TiCl3]·THF (3) activated by methylalumoxane (MAO) has been compared in the polymerization of ethylene and propylene. Despite structural and symmetrical differences, the activities of all precatalysts were found to be alike, indicating that rearrangements toward similar active species are operative during the polymerization regardless of the starting materials. To shed some light on the mechanistic pathways for the formation of such active species from the different titanium benzamidinate complexes and on the role of the aluminum cocatalyst in the activation process, corresponding aluminum benzamidinate dichloro and dimethyl complexes were synthesized and compared to the titanium complexes. The formation of the different active sites was monitored using NMR and ESR spectroscopy, trapping experiments with [60]fullerene, and MALDI-TOF mass spectroscopy. The results obtained for the different benzamidinate titanium complexes and proposed mechanistic pathways for their activation reactions with MAO and their fate after the addition of the olefins are presented and discussed in this publication. In addition, viscoelastic and rheological mechanical properties of the polymers are disclosed.

Original languageEnglish
Pages (from-to)2656-2666
Number of pages11
JournalOrganometallics
Volume25
Issue number10
DOIs
StatePublished - 8 May 2006
Externally publishedYes

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