Synthesis And Characterization Of Nitrogen-bridged Bis(Phenolate) And Amidate Lanthanide(La/Gd) Complexes And Their Catalytic Behavior

In this thesis,a series of amine-bridged bis（phenols）and N-substituted benzamide ligands were designed and synthesized,and the corresponding lanthanium and gadolinium complexes were synthesized.The complexes obtained were characterized by elemental analysis,infrared,nuclear magnetic resonance（NMR）.The catalytic properties and mechanism of the complexes on the ring-opening polymerization ofε-caprolactone have been studied.The research work includes the following two parts:Part one:Synthesis and structure of amine-bridged bis（phenolate）lanthanide complexes and their application in the polymerization ofε-caprolactoneFour amine-bridged bis（phenolate）ligands Et₂N（CH₂）₃N[CH₂-2-OH-3,5-（^tBu）₂-C₆H₂]₂（H₂L₁）,Et₂N（CH₂）₃N[CH₂-2-OH-3-^tBu-5-Me-C₆H₂]₂（H₂L₂）,ⁱPr N[CH₂-2-OH-3,5-（^tBu）₂-C₆H₂]₂（H₂L₃）,ⁱPr N[CH₂-2-OH-3-^tBu-5-Me-C₆H₂]₂（H₂L₄）were obtained by Mannich reaction via different substitutional groups of phenol and pr imary amine.A series of amine-br idged bis（phenolate）complexes L₁La[N（Si Me₃）₂]（2a）、L₁Gd[N（Si Me₃）₂]（2b）、L₂La[N（Si Me₃）₂]（2c）、L₂Gd[N（Si Me₃）₂]（2d）、L₃La[N（Si Me₃）₂]（2e）、L₃Gd[N（Si Me₃）₂]（2f）、L₄La[N（Si Me₃）₂]（2g）、L₄Gd[N（Si Me₃）₂]（2h）were synthesized by amine elimination reaction of amine-bridged bis（phenolate）ligands with Ln[N（Si Me₃）₂]₃（Ln=La,Gd）in a ratio of 1:1.The catalytic properties of amine-bridged bis（phenolate）complexes on the ring-opening polymerization ofε-caprolactone have been studied and the results showed that all complexes are efficient initiators for this ring-opening polymer ization reaction.The NMR spectrum of oligomer ofε-caprolactone revealed that the ROP ofε-caprolactone proceeded via a coordination–insertion mechanism.Part two:Synthesis and characterization of N-substituted benzamide lanthanide complexes and their application in the polymerization ofε-caprolactone.Five N-substituted benzamide ligands Bz NHPh（HL₁）、Bz NHPh-p（HL₂）、Bz NHPh Me-o（HL₃）、Bz NHPh（2-Me-6-Et）（HL₄）、Nz NHPh Et-o（HL₅）]were obtained by amidation reaction of benzoyl chloride and primary amine.Ten N-substituted benzamide lanthanide complexes[（Bz NPh）₃La（3a）、（Bz NPh）₃Gd（3b）、（Bz NPh-p）₃La（3c）、（Bz NPh-p）₃Gd（3d）、（Bz NPh Me-o）₃La（3e）、（Bz NPh Me-o）₃Gd（3f）、[Bz NPh（2-Me-6-Et）]₃La（3g）、[Bz NPh（2-Me-6-Et）]₃Gd（3h）、（Nz NPh Et-o）₃La（3i）、（Nz NPh Et-o）₃Gd（3j）were synthesized by amine elimination reaction of N-substituted benzamide ligands with Ln[N（Si Me₃）₂]₃（Ln=La,Gd）in a ratio of 3:1.The catalytic properties of N-substituted benzamide lanthanide complexes on the ring-opening polymer ization ofε-caprolactone have been studied,and the results showed that all complexes are efficient initiators for this ring-opening polymerization reaction.The NMR spectrum of oligomer ofε-caprolactone revealed that the ROP ofε-caprolactone proceeded via a coordination–insertion mechanism.