Heterolepic -Ketoiminate Zinc Phenoxide Complexes as Efficient Catalysts for the Ring Opening Polymerization of Lactide.

Zinc phenoxide complexes LZnOAr - (L=MeNCHNC(Me)CHC(Me)O) and LZnOAr - (L=MeNCHNC(Me)CHC(Me)O) with donor-functionalized -ketoiminate ligands (L) and OAr substituents (Ar=Ph , ; 2,6-Me-CH , ; 3,5-Me-CH , ; 4-Bu-CH , ) with tuneable electronic and steric properties were synthesized and characterized. - adopt binuclear structures in the solid state except for , while they are monomeric in CDCl solution. - are active catalysts for the ring opening polymerization (ROP) of lactide (LA) in CHCl 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 ( ) and moderately controlled molecular weight distribution (MWDs). and showed a living polymerization character and kinetic studies on the ROP of -LA with and proved first order dependencies on the monomer concentration. Homonuclear decoupled H-NMR analyses of polylactic acid (PLA) formed with -LA proved isotactic enrichment of the PLA microstructure.