Influence of π-ligand substitutions on the regiospecificity and stereospecificity in isospecific zirconocenes for propene polymerization. A molecular mechanics analysis

Massimiliano Toto, Luigi Cavallo, Paolo Corradini, Gilberto Moscardi, Luigi Resconi, Gaetano Guerra*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

58 Scopus citations

Abstract

A possible rationalization of the dependence of regiospecificity of propene polymerization for catalytic systems based on C 2 -symmetric ansa-zirconocenes (and hafnocenes) on the π-ligand alkyl substitutions is presented. With this aim, models of preinsertion intermediates and transition states for primary and secondary monomer insertion reactions are compared through molecular mechanics analyses. The nonbonded energy contributions to the regioselectivity, as well as the enantioselectivities of regioregular and regioirregular insertion steps have been investigated. Nonbonded energy interactions are able to account for the increases of regiospecificity experimentally observed for zirconocene-based catalytic systems when the π-ligands are alkyl substituted in position 2 or 3 as well as the decrease of regiospecificity observed when the π-ligands are dimethyl substituted in positions 4 and 7.

Original languageEnglish (US)
Pages (from-to)3431-3438
Number of pages8
JournalMacromolecules
Volume31
Issue number11
DOIs
StatePublished - Jun 2 1998

ASJC Scopus subject areas

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

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