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

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.