| Abstract: | Monomeric bis(isopropoxy) titanium complexes LTi(Oi Pr)2 (L = ─ OC6H2–4‐R1–6‐R2–2‐CH2N(CH2)2N(R3)2]CH2–4‐R4–6‐R5‐C6H2O ─ , R1 = R2 = t Bu, R3 = Et, R4 = R5 = Cl, (L1)Ti(Oi Pr)2; R1 = R2 = Me, R3 = Et, R4 = R5 = Me, (L2)Ti(Oi Pr)2; R1 = R2 = t Bu, R3 = Et, R4 = OMe, R5 = t Bu, (L3)Ti(Oi Pr)2; R1 = R4 = OMe, R3 = Et, R2 = R5 = t Bu, (L4)Ti(Oi Pr)2; R1 = R2 = t Bu, R3 = Me, R4 = OMe, R5 = t Bu, (L5)Ti(Oi Pr)2) supported by amine bis(phenolate) ligands were synthesized and characterized using NMR spectroscopy and elemental analysis. The solid‐state structure of (L3)Ti(Oi Pr)2 was determined using single‐crystal X‐ray diffraction. (L1–5)Ti(Oi Pr)2 were all found to initiate the ring‐opening polymerization of l ‐lactide and rac ‐lactide in a controlled manner at 110–160°C. As shown by kinetic studies, (L1)Ti(Oi Pr)2 polymerized l ‐lactide faster than did (L2–5)Ti(Oi Pr)2. In addition, good number‐average molecular weight and narrow polydispersity index (1.00–1.71) of polymers were also obtained. The microstructure of the polymers and a possible mechanism of coordination–insertion of polymerization were evidenced by MALDI‐TOF and 1H NMR spectra of the polylactides. |
