Dimethylaluminium aldiminophenolates: synthesis, characterization and ring-opening polymerization behavior towards lactides

Abstract

The stoichiometric reaction of the salicylaldimine derivatives (L1–L12) with trimethylaluminium afforded the corresponding dimethylaluminium aldiminophenolates (C1–C12), which were fully characterized by NMR spectroscopy and elemental analysis. The molecular structures of the representative complexes C1, C6, and C8 were determined by the single-crystal X-ray diffraction, which revealed distorted tetrahedral geometry at aluminium. Activation of the dimethylaluminium aldiminophenolates for the ring-opening polymerization required one equivalent of BnOH. On the basis of the polymerization results for L-lactide, D-lactide or rac-lactide, higher efficiency was observed for the ROP of D-lactide, and the nature of the ligands present significantly affected the observed catalytic activities and the properties of the resultant polylactides.