Ti and Zr complexes bearing guanidine-phenolate ligands: coordination chemistry and polymerization studies.

ABSTRACT: A series of group 4 bis(isopropoxide) complexes M[N^O]₂(OⁱPr)₂, stabilized by guanidine-phenolate N^O ligands, have been prepared and used as catalysts for the polymerization of unpurified rac-lactide under solvent-free conditions at 130 °C. The resulting polylactic acid (PLA) presented heterotactic bias (P _r = 0.56-0.62) with molecular weights similar to those obtained in control experiments with Zr(OⁱPr)₄·ⁱPrOH, Ti(OⁱPr)₄, and Sn(Oct)₂. The molecular weights were lower than expected for living polymerization due to chain transfer and/or transesterification. Zr complexes were more active than the Ti homologues, with rate constants ranging from 1.17-3.21 × 10^-4</

SUBMITTER: Flores-Romero V 

PROVIDER: S-EPMC11328681 | biostudies-literature | 2024 Aug

REPOSITORIES: biostudies-literature