Ring-opening polymerisation of rac-lactide mediated by cationic zinc complexes featuring P-stereogenic bisphosphinimine ligands

Dalton Trans. 2012 Apr 7;41(13):3701-13. doi: 10.1039/c2dt11954d. Epub 2012 Feb 15.

Abstract

The diastereomerically pure P-stereogenic bis(phosphinimine) ligands 4,6-(ArN[double bond, length as m-dash]PMePh)(2)dbf [Ar = 4-isopropylphenyl (Pipp): rac-4, meso-4; Ar = 2,6-diisopropylphenyl (Dipp): rac-4a; dbf = dibenzofuran] were synthesised and complexed to zinc using a protonation-alkane elimination strategy. The cationic alkylzinc complexes thus obtained, RZn[4,6-(ArN[double bond, length as m-dash]PMePh)(2)dbf][B(Ar')(4)] [Ar = Pipp, Ar' = C(6)H(3)(CF(3))(2): rac-6 (R = Et), meso-6 (R = Et), rac-7 (R = Me) meso-7 (R = Me); Ar = Dipp: rac-6a (R = Et, Ar' = C(6)H(3)(CF(3))(2)), rac-6b (R = Et, Ar' = C(6)F(5))] were investigated for their competency as initiators for the ring-opening polymerisation of rac-lactide. The formation of polylactide was achieved under relatively mild conditions (40 °C, 2-4 h) and the microstructures of the resulting polymers exhibited a slight heterotactic bias [polymer tacticity (P(r)) = 0.51-0.63].

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Dioxanes / chemistry*
  • Ligands
  • Models, Molecular
  • Molecular Conformation
  • Organometallic Compounds / chemistry*
  • Phosphines / chemistry*
  • Polymerization*
  • Stereoisomerism
  • Zinc / chemistry*

Substances

  • Dioxanes
  • Ligands
  • Organometallic Compounds
  • Phosphines
  • dilactide
  • Zinc