Synthesis And Characterization Of Organolanthanide(Ⅲ) Amidate Complexes And Their Reactive Behavior

Based on benzamide ligand （L=[C₆H₅CON（2,6-iPr₂-C₆H₃）]）, two series of theanionic and neutral organolanthanide（Ⅲ） complexes were synthesized in this thesis. Allthe complexes were fully characterized by various techniques including X-ray singlecrystal diffraction. Meanwhile, their catalytic properties for the ring-openingpolymerization of esters and the reactivities to PhNCO were comparatively observed.Furthermore, studies on the synthesis of organolanthanide amidate complexesderivatives （for instance, cyclopentadienyl-or aryloxy-） were preliminarily carried out.The main results were listed below.1Reactions of anionic lanthanide amido complex LiLn（NⁱPr₂）₄（THF） with HL in1:4molar ratio afforded anionic lanthanide amidate complexesLi（THF）Ln[OC（C₆H₅）N（2,6-iPr₂-C₆H₃）]₄（THF）_n（Ln=La （1）, Nd （2）, Sm （3）, Yb （4）, Y（5）, n=0or1）. It was found that, the four amidate groups took on diverisities incoordination modes, and the structures of the complexes varied with the ionic radii. Allthe anionic complexes were characterized by elemental analysis and IR spectroscopy,with additional¹H NMR and¹³C NMR spectroscopy in the case of complexes1and5.Their structures were determined by X-ray single crystal diffraction.2Reactions of neutral homoleptic lanthanide amides Ln[N（SiMe₃）₂]₃with HL in1:3molar ratio afforded three neutral lanthanide amidate complexes,Ln[OC（C₆H₅）N（2,6-iPr₂-C₆H₃）]₄（μ-H）（THF）2（Ln=La （6）, Nd （7）, Sm （8））. Theirstructures were characterized by elemental analysis, IR spectroscopy and X-ray singlecrystal diffraction, with additional¹H NMR spectroscopy in the case of complexes6.The three neutral lanthanide amidate complexes were isomorphous and C2-symeritric.Two of the four amidate groups chelat to the lanthanide metal, and meanwhile the othertwo coordinate to the metal in a monodentate method, bridging each other through a N---H---N bond.3The catalytic activity of anionic neodymium amidate complex for thering-opening polymerization （ROP） of ε-caprolactone was preliminarily tested. Theresults showed, it catalyzed the ROP of ε-caprolactone with high activity, resulting inpolyester with large molecular weight （Mn>10⁴） and medium molecular weightdistributions （PDI=1.90-1.98）.4Both the anionic and neutral lanthanide amidate complexes were proved to beefficient catalysts for the ROP of L-lactide, and the neutral ones exhibited more active.Their reactivities increased while the ionic radii of lanthanide metals became bigger.The molecular weights of polylactide obtained from these two catalytic reations weredeviated from the calculated ones dramatically, and the PDIs, varied from1.21to1.50,were medium.5Both the anionic and neutral lanthanide amidate complexes catalyzed the ROP ofrac-lactide, affording heterotactic-rich polylactides. The anionic complexes showedhigher catalytic activities than their neutral counterpart. The central metals had a stronginfluence on their activities. For the anionic complexes, the decreasing order of thereactivity, that is, La> Nd> Sm> Y> Yb, was observed. However, the trend inreactivity of the neutral lanthanide amidate complexes was La <Nd <Sm.6Reactions of anionic lanthanide amidate complex2with PhNCO in1:1molarratio afforded product9resulted from the insertion of PhNCO into the Nd-N bond.Complex9was characterized by IR spectroscopy and X-ray single crystal diffraction.7The syntheses of organolanthanide amidate complexes derivatives werepreliminarily studies.a) The potassium salt was formed in situ with the reaction of HL and KH, then1equivalent of bisaryloxo lanthanide chloride was added to undergo metathesis reaction.After workup, the target aryloxy derivative10was obtained.b) Direct protonolysis reaction of Cp3Ln（THF） with HL in1:1molar ratio resultedin the formation of cyclopentadienyl derivatives [Cp2Ln（OC（C₆H₅）N（2,6-iPr₂-C₆H₃））]₂（Ln=Yb （11）, Sm （12））.c) Protonolysis reaction of Cp3Nd（THF） with HL in1:2molar ratio resulted in the formation of complex [Cp2Nd（OC（C₆H₅）N（2,6-iPr₂-C₆H₃））]₂（13）, which wasisomorphous with12.Complexes10-13were characterized by elemental analysis and IR spectroscopy,with the structures of10,12and13determined by X-ray single crystal diffraction.