Key elements in the structure and function relationship of the MgCl 2/TiCl4/Lewis base Ziegler-Natta catalytic system

Andrea Correa*, Fabrizio Piemontesi, Giampiero Morini, Luigi Cavallo

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

114 Scopus citations

Abstract

We present a theoretical study of the basic interactions occurring at supported hetereogenous Ziegler-Natta catalytic systems. We first investigated the interaction between prototypes of each class of industrially relevant internal donors (1,3-diethers, alkoxysilanes, phthalates, succinates) and the MgCl2 support. Our analysis indicates that donors can be separated into two classes. 1,3-Diethers and alkoxysilanes belong to the former because they have a short spacer between the coordinating O atoms and coordinate preferentially to the same Mg atom of the (110) lateral cut. Conversely, phthalates and succinates belong to the latter class because they have a longer spacer between the coordinating O atoms and thus can adopt a variety of coordination modes. Indeed, they can coordinate to both the (100) and (110) lateral cuts. In the last part of this manuscript we report on the stereo- and regioselective behavior of possible active Ti species with and without two succinate molecules coordinated in the proximity of the Ti atom. We show that the two succinate molecules confer a remarkable stereoselectivity in both primary and secondary propene insertions. This model very simply rationalizes the effect of the donors, and it is consistent with the models so far developed to rationalize the stereoselectivity of metallocene and octahedral nonmetallocene catalysts.

Original languageEnglish (US)
Pages (from-to)9181-9189
Number of pages9
JournalMacromolecules
Volume40
Issue number25
DOIs
StatePublished - Dec 11 2007

ASJC Scopus subject areas

  • Organic Chemistry
  • Polymers and Plastics
  • Inorganic Chemistry
  • Materials Chemistry

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