Mechanism of stereocontrol in methyl methacrylate polymerization promoted by C1-symmetric metallocenes

Lucia Caporaso, Luigi Cavallo*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

19 Scopus citations

Abstract

The mechanism of stereoselectivity in methyl methacrylate (MMA) monometallic polymerization promoted by the C1-symmetric ansa-Me 2C(Cp)(Ind)Zr-based zirconocene, presenting two diastereotopic coordination sites, was investigated within density functional theory. At variance from the case of propene polymerization, our results suggest that MMA addition is stereoselective when the growing chain is in the more hindered as well as in the more open diastereotopic coordination site. In both cases the same enantioface of the enolate bond of the ester enolate growing chain is selected, although selectivity is higher when the growing chain is in the more hindered diastereotopic coordination site. Further, there is no substantial energy difference between these two situations, which indicates that the moderate isotacticity of the produced PMMA is consistent with an almost regular chain-migratory mechanism. The different stereoselectivity of the two diastereotopic sites is due to different steric interaction between the growing chain (chain effect) or MMA (monomer effect) with the indenyl ligand. This decomposition of stereoselectivity into chain and monomer effects is used to reinvestigate the stereoselectivity of strictly related C2- and Cs-symmetric zirconocenes.

Original languageEnglish (US)
Pages (from-to)3439-3445
Number of pages7
JournalMacromolecules
Volume41
Issue number10
DOIs
StatePublished - May 27 2008

ASJC Scopus subject areas

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

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