| A series of anionic phenoxy-amido rare-earth metal amide supported by the dianionic phenoxy-amido ligands were synthesized, and their catalytic activity for the polymerization of L-lactide were studied. The aminophenol ligands used in this thesis are as follows: N-p-methyl-phenyl(2-hydroxy-3,5-di-tert-butyl)benzylamine [NO]1H2, N-p-fluorin-phenyl(2-hydroxy-3,5-di-tert-butyl)benzylamine [NO]2H2, N-p-chlorin-phenyl(2-hydroxy-3,5-di-tert-butyl)benzylamine [NO]3H2, N-p-bromine-phenyl (2-hydroxy-3,5-di-tert-butyl)benzylamine [NO]4H2. The main results obtained are as follows:1. Reactions of [NO]1H2 with BunLi or Na in a 1:1 molar ratio in THF solution gave the lithium aminophenoxy [HNOLi(THF)]2 (1) and sodium aminophenoxy [HNONa(THF)]2 (2) in high yields. Complexes 1 and 2 were characterized by IR elemental analysis, and NMR spectroscopy. Structural determination revealed that they have solvated dimeric structure in solid state.2. The stoichiometric reactions of Ln[N(TMS)2]3(μ-Cl)Li(THF)3 with the lithium aminophenoxy generated in situ in tetrahydrofuran (THF) gave the anionic rare-earth metal amido complexes [NO]12Ln[N(TMS)2][Li(THF)]2 [Ln = Pr (3) Nd (4), Sm (5), Yb (6), Y (7)], [NO]22Ln[N(TMS)2][Li(THF)]2 [Ln = Pr (8) Nd (9), Sm (10), Yb (11)], [NO]32Ln[N(TMS)2][Li(THF)]2 [Ln = Pr (12) Sm (13), Yb (14), Y (15)], [NO]42Ln[N(TMS)2][Li(THF)]2 [Ln = Pr (16) Nd (17), Sm (18), Yb (19), Y (20)] in high isolated yields. All of these complexes were fully characterized. X-Ray structure determination revealed that complexes 3?20 are isostructural, and have solvated monomeric structures. 3. The catalytic behavior of complexes 3?7 for the ring-opening polymerization of L-lactide was explored. These complexes showed high activity towards L-lactide polymerization to give the polymers with high molecular weight, but with relatively wide molecular weight distributions. The ionic radii of the central metals have a significant effect on the catalytic activity.4. The lithium aminophenoxy [HNOLi(THF)]2 (1) and sodium aminophenoxy [HNONa(THF)]2 (2) can also initiate the ring-opening polymerization of L-lactide with moderate activity in a uncontrolled manner. |
