Synthesis And Characterization Of β-diketiminato Lanthanide Amido Complexes

A series of diketiminato lanthanide amino complexes were synthesized, and wellcharacterized. It was found the first time that the C-O bond on the diketiminato can beactivated promoted by the lanthanide amido complex under suitable conditions. The catalyticbehavior of these lanthanide complexes for the ring-opening polymerization of L-lactide wasexplored. The-diketiminate ligand BDI-H used in this thesis is2-(2-methoxy)anilino-4-(2,6-diisopropyl)anilino-2-amylene, BDIs-H is2-(2-methylthio)anilino-4-(2,6-diisopropyl)anilino-2-amylene, and BDI’ is the ligand of BDI underwent C-Obond cleavage.1. Reactions of BDI-H with Ln[N(TMS)2]3(-Cl)Li(THF)3in a1:1molar ratio intoluene at110oC for48h gave the unexpected [(BDI’)LnN(TMS)2]2(Ln=Sm (1), Yb (2),Y (3)), in which the C-O bond on the diketiminato ligand was cleaved. All of thesecomplexes were characterized by IR spectroscopy, elemental analysis, and1H NMRspectroscopy in the case of complex3. X-ray crystal structure determination revealed thatcomplexes1-3have dinuclear structures in the solid state.2. It was found that reaction temperature plays a crucial role for the reaction ofBDI-H with Ln[N(TMS)2]3(-Cl)Li(THF)3. When the same reactions were conducted in a1:1molar ratio in toluene at room temperature, the desired diketiminato lanthanidebis(amido) complexes (BDI)Ln[N(TMS)2]2(Ln=Sm (4), Yb (5), Y (6)) can be obtained ingood isolated yields. These complexes were characterized by elemental analysis. X-raycrystal structure determination revealed that all of these complexes have monomericstructure in solid state. It was found that complex4-6can initiate the ring-openingpolymerizations of L-lactide.3. Further study revealed that the ionic radius of lanthanide metal also has influenceon the reaction of BDI-H with Ln[N(TMS)2]3-Cl)Li(THF)3. For the neodymium, which has relatively larger ionic radius, only the diketiminato lanthanide bis(amido) complexes(BDI)Nd[N(TMS)2]2(7) can be isolated wether the reaction of BDI-H withNd[N(TMS)2]3-Cl)Li(THF)3was conducted at110oC or at room temperature in toluene.4. It was found that the steric bulkiness of the raw material has influence on thereaction. Reaction of BDI-H with Y[N(HSiMe2)2]3(THF)2in a1:1molar ratio in toluene at110oC for48h gave the expected (BDI)Y[N(HSiMe2)2]2(8) in good isolated yield.However, the reactions of BDI-H with Y[N(TMS)2]2Cl in a1:1molar ratio in toluene at110oC for48h gave the unexpected (BDI’)Y(-Cl)2Y(BDI)(9) as the final product. Thesecomplexes were characterized by elemental analysis and crystal structure determination.5. It was found that the lanthanide amido complex can not promote the C-S bondactivation of the diketiminato ligand. Reaction of BDIs-H withSm[N(TMS)2]3(-Cl)Li(THF)3in a1:1molar ratio in toluene at110oC for48h gave thesamarium complex [(BDIs)SmN(TMS)2(-Cl)]2(10). This complex was characterized byelemental analysis and crystal structure determination.