Bis(aniline–phenolate) complexes of group 4 metals: Coordination chemistry and lactide polymerization catalysis

The substituted aniline–phenol ligand binds in the reduced-monoanionic form to the group 4 metals giving fluxional octahedral [{NO}2M(OR)2]-type complexes. The X-ray structures of the Zr- and Hf-complexes revealed cis-N/trans-O binding and an overall C1 symmetry. All three complexes exhibited high activities in polymerization of L-lactide and rac-lactide. The Zr- and Hf-complexes led to heterotactically enriched PLA.