Homoleptic and heteroleptic ketodiiminate zinc complexes for the ROP of cyclic l-lactide

Homo- and heteroleptic ketodiiminate zinc complexes (L2Zn2)-Zn-1 (1, L-1 = [Me2NC2H4NC(Me)CH](2)CO), L-2(ZnCp)(2) (2, L-2 = [Me2NC3H6NC(Me)CH](2)CO, Cp = C5H5) and (LHZnCp)-H-2* (3, Cp* = C5Me5) were synthesized and characterized by H-1 and C-13 NMR and IR spectroscopy as well as by elemental analysis and single crystal X-ray diffraction (sc-XRD, 2, 3). The catalytical activity of heteroleptic complexes 2 and 3 were tested in the ring-opening polymerization (ROP) of L-lactide. Homobimetallic complex 2 showed the highest activity and selectivity for the synthesis of cyclic polylactide (cPLLA; TOF = 17 460 h(-1)) at 100 degrees C in toluene solution, while linear polymers are formed with mononuclear complex 3

Automated summary

In this study, three zinc complexes were synthesized and characterized using various techniques. The results indicated that heteroleptic complex 2 exhibited the highest activity and selectivity in the ring-opening polymerization reaction.