Syntlhesis, Structures And Catalytic Properties Of Organometallic Compounds Basedon β-diketiiminate Ligand

This thesis presents the studies on the synthesis,structures and catalytic properties of aluminum,zinc and rare earth metal compounds based onβ-diketiminate ligand.It includes the following three parts.Firstly,the asymmetricβ-diketiminate ligand HL¹（N-{4-[（2,6-diisopropyl-phenyl）imino]pent-2-en-2-yl}pyridin-2-amine）was synthesized.Reactions of HL¹ with AlMe₃,Et₂AlCl,and AlEtCl₂,respectively,afforded[Al（L）Me₂]（1）,[Al（L）EtCl]（2）,and[Al（L）Cl₂]（3）in high yields.The structures of 1-3 were established by single-crystal X-ray diffraction,¹H NMR and ¹³C NMR.They were tested as precursors in the ring-opening polymerization（ROP）ofε-caprolactone in the absence and presence of benzyl alcohol.With addition of one equivalent of benzyl alcohol,all complexes were efficient initiators for the ROP ofε-caprolactone.The catalytic behaviors of 1 and 2 are similar,whereas their catalytic performances exhibit a marked difference to that of 3.MALDI-TOF-MS studies for the end group analysis were conducted.Secondly,reaction of HL¹ with ZnEt₂ gave[Zn₂（L）₂Et₂]（4）.The structure of 4 was established by single-crystal X-ray diffraction and ¹H NMR.It was tested as precursors in the ring-opening polymerization ofε-caprolactone in the absence and presence of benzyl alcohol.Compared to complexes 1-3,complex 4 was the most active one in the absence of benzyl alcohol.Compound 4 catalyzes ring-opening polymerization ofε-caprolactone within 3 hours to yield a polymer with the molecular weight of more than 140,000.In the presence of benzyl alcohol,the catalytic efficiency of compound 4 is remarkably improved.Finally,the ketoiminate ligand H₂L²（4-（（1-hydroxy-2,3-dihydro-1H-inden-2-yl）amino）pent-3-en-2-one）was synthesized.Reactions of HL¹ and H₂L² with Y（CH₂SiMe₃）₃ and Sc（N（SiMe₃）₂）₃,respectively,afforded[L₂Y]（5）and[L₄²ScNa]（6）.The two compounds did not show significant activity on the ring-opening polymerization ofε-caprolactone because the central metals of the two compounds did not have a reactive group and the steric hindrance of central metal for each compound was too large.