Synthesis And Structure Characterization Of Homoleptic Lanthanide Complexes Stabilized By Schiff-base Ligands And Organoaluminium Complexes Stabilized By Carbon-Bridged Bis (phenolate) Ligands And Their Catalytic Behavior

In this thesis,a series of lanthanide/gadolinium complexes bearing functionalized aryloxide ligands and organoaluminium complexes supported by carbon-bridged bis?phenolate?ligands were designed and synthesized.The complexes obtained were characterized by elemental analysis,infrared,¹H NMR,¹³C NMR and X-ray single crystal diffraction.The catalytic properties of the complexes on the ring-opening polymerization of?-caprolactone have been studied.The research work includes the following two parts:Part one:Synthesis and structure characterization of homoleptic lanthanide complexes stabilized by Schiff-base ligands and their application in the polymerization of?-caprolactone.A series of homoleptic lanthanide complexes[?L1–4?3Ln]?Ln=La,L1 2a,L2 2c,L3 2e,L4 2g;Ln=Gd,L1 2b,L2 2d,L3 2f,L4 2h?supported by Schiff-base ligands were synthesized by the amine elimination reactions of monophenol ligands[2,4-^tBu2-6-CH=N-C6H4-o-CH3-PhOH?HL1?,2,4-^tBu2-6-CH=N-C6H4-o-C2H5-PhOH?HL2?,2,4-^tBu2-6-CH=N-C6H4-p-OC2H5-PhOH?HL3?,2,4-^tBu2-6-CH=N-C6H4-p-Cl-PhOH?HL4?]with Ln[N?SiMe3?2]3?Ln=La,Gd?in 3:1 M ration in THF.Complexes 2a,2c,2e and 2g were characterized by NMR spectra and all eight complexes were characterized using elemental analysis and infrared spectra.Complexes 2b,2c and 2d have been determined by single-crystal X-ray diffraction,which reveals that they have possessed isostructual unsolvated mononuclear structures and the metal center has exhibited a distorted octahedral geometry,in which the O?1?,O?2?,O?3?atoms have occupied three positions and N?1?,N?2?,N?3?atoms have occupied the other three positions.The catalytic properties of complexes 2a-2g for the ring-opening polymerization of?-caprolactone were studied and found that all complexes were efficient initiators for this ring-opening polymerization reaction that afforded polycaprolactone with high molecular weights and moderate molecular-weight distributions.Part two:Organoaluminium complexes supported by carbon-bridged bis?phenolate?ligands:synthesis,structure and their application in the polymerization of?-caprolactone.Reaction of bisphenol ligands H2L1-6[L=PhCH?C6H2-3-^tBu-5-R-2-O?2:R=^tBu,H2L1 and R=Me,H2L2;L=?p-CH3?PhCH?C6H2-3-^tBu-5-R-2-O?2:R=^tBu,H2L3 and R=Me,H2L4;L=?o-OCH3?PhCH?C6H2-3-^tBu-5-R-2-O?2:R=^tBu,H2L5 and R=Me,H2L6]with slightly greater than one equivalent of triethyl aluminium in coordinating solvent THF at room temperature afforded solvated monomeric aluminium bisphenoxides L1-6AlEt?THF?[L1,3b;L2,3c;L3,3d;L4,3e;L5,3f;L6,3g].However,treating triethyl aluminium with the ligand H2L1 in toluene at room temperature,unsolvated dimeric{L1AlEt}2?3a?was obtained unexpectedly.Complexes 3a-3g were characterized by NMR spectra,infrared spectra and elemental analysis.Complexes 3a has been determined by single-crystal X-ray diffraction,which reveals that the metal center is coordinated by three oxygen atoms and one carbon atom has exhibited a distorted tetrahedron geometry.The catalytic properties of these complexes for the ring-opening polymerization of?-caprolactone were investigated and found that all complexes were efficient initiators for ring-opening polymerization reaction.What's more,variation of the substituent on the aryl ring of ligand was shown to have a considerable influe nce on the catalysis result.