Heterolepic β ‐Ketoiminate Zinc Phenoxide Complexes as Efficient Catalysts for the Ring Opening Polymerization of Lactide

S. Ghosh, P.M. Schafer, D. Dittrich, C. Scheiper, P. Steiniger, G. Fink, A.N. Ksiazkiewicz, A. Tjaberings, C. Wolper, A.H. Groschel, A. Pich, S. Herres-Pawlis*, S. Schulz*

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

13 Citations (Web of Science)

Abstract

Zinc phenoxide complexes (LZnOAr)-Zn-1 1-4 (L-1=Me2NC2H4NC(Me)CHC(Me)O) and (LZnOAr)-Zn-2 5-8 (L-2=Me2NC3H6NC(Me)CHC(Me)O) with donor-functionalized beta-ketoiminate ligands (L-1/2) and OAr substituents (Ar=Ph 1, 5; 2,6-Me-2-C6H3 2, 6; 3,5-Me-2-C6H3 3, 7; 4-Bu-C6H4 4, 8) with tuneable electronic and steric properties were synthesized and characterized. 1-8 adopt binuclear structures in the solid state except for 5, while they are monomeric in CDCl3 solution. 1-8 are active catalysts for the ring opening polymerization (ROP) of lactide (LA) in CH2Cl2 at ambient temperature and the catalytic activity is controlled by the electronic and steric properties of the OAr substituent, yielding polymers with high average molecular weight (M-n) and moderately controlled molecular weight distribution (MWDs). 1 and 5 showed a living polymerization character and kinetic studies on the ROP of L-LA with 1 and 5 proved first order dependencies on the monomer concentration. Homonuclear decoupled H-1-NMR analyses of polylactic acid (PLA) formed with rac-LA proved isotactic enrichment of the PLA microstructure.
Original languageEnglish
Pages (from-to)951-960
Number of pages10
JournalChemistry Open
Volume8
Issue number7
DOIs
Publication statusPublished - 1 Jul 2019

Keywords

  • aluminum complexes
  • coordination chemistry
  • diastereoselective synthesis
  • epsilon-caprolactone
  • ketoiminate
  • lactide
  • lewis pairs
  • magnesium
  • polymerization reactions
  • single-site catalysts
  • stereoselective polymerization
  • structural-characterization
  • substituent effects
  • tridentate ketiminate ligands
  • zinc
  • COORDINATION CHEMISTRY
  • STRUCTURAL-CHARACTERIZATION
  • ALUMINUM COMPLEXES
  • STEREOSELECTIVE POLYMERIZATION
  • TRIDENTATE KETIMINATE LIGANDS
  • LEWIS PAIRS
  • MAGNESIUM
  • EPSILON-CAPROLACTONE
  • DIASTEREOSELECTIVE SYNTHESIS
  • SINGLE-SITE CATALYSTS

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