Rare Earth Complexes Bearing Anilido-Oxazolinate Ligands: Synthesis,Characterization And Their Catalytic Performance

In this thesis,the anilido-oxazolinate rare earth metal complexes were designed and synthesized for the first time,and the exact structure of the complexes were determined by NMR,IR spectroscopy and X-ray single crystal diffraction.In addition,the properties of the complexes in catalyzing the polymerization of isoprene and cycloesters were studied.The specific research contents is as follows:Anilido-oxazoline alkyl complexes 1-7?Sc,Y and Lu?were designed and synthesized.The complexes were characterized by NMR spectroscopy and single crystal diffraction.X-ray single crystal diffraction indicated that complexes 1 and 3-6 exhibit distorted trigonal bipyramidal configuration,while complex 2 is pseudo-tetrahedral without coordinated THF.Complexes 1-6 exhibited blue-green fluorescence at the excitation wavelength of 400 nm,and the maximum emission wavelength was 465-477 nm.The reasons for the unique electronic structure and luminescence characteristics of the complexes were investigated by theoretical calculation.Upon activation with organic borates,the complexes 1-7 can catalyze the polymerization of isoprene with high activity.The resulting polymer shows high cis-1,4-selectivity,and the highest cis-1,4-selectivity is 96.1%.It was shown that the type of central metal and the oxazoline substituent groups signficantly affected the polymerization selectivity.The complexes 1-6 can also initiate ring opening polymerization of?-caprolactone.When the center metals are yttrium and lutetium,the complexes exhibited very high polymerization activity and the conversion rate is over 98%within 1 min.In addition,the system can also be the catalyzed caprolactone and isoprene copolyme,get a isoprene-caprolactone block copolymer?PIP-b-PCL?,through changing the weight ratio of caprolactone,can adjust the water contact angle of block copolymer?121.3°-93.3°?and improve the surface properties of the polyolefin material.Anilido-oxazoline rare-earth metal complexes 8-17 containing chiral groups were designed and synthesized.The complexes were characterized by NMR spectroscopy and single crystal diffraction.X-ray single crystal diffraction indicated that complexes 8 and11-13 were all distorted trigonal bipyramidal configuration.Both complexes 8-17 can catalyze ring opening polymerization of racemic lactide with high activity.Scandium complexes showed excellent activity,TOF value up to 720 h^-1?THF,25°C?and 2910 h^-1?toluene,60°C?,which is among the highest in the current report system of scandium catalytic reactivity.The polylactide catalyzed by scandium complexes showed heteroselectivity?P_r=0.59–0.71?.The polymerization activity of yttrium complexes were superior to the corresponding scandium complexes.At room temperature,the TOF value up to 1176 h^-1?THF,25°C?and the heteroselectivity was P_r=0.75.Studies on reaction kinetics and reaction mechanism showed that the initiator group was alkyl group on metal,and the polymerization system was controllable.