Novel Rare Earth Metal Complexes With Chiral Carbene:Synthesis And Catalytic Performance

Three kinds of chiral N-heterocyclic carbene rare earth metal complexes were designed and synthesized for the first time in this paper,and the catalytic properties of the complexes on the catalytic properties of isoprene and?-olefin were investigated in depth.The main contents are as follows:Three kinds of Bisoxazoline N-Heterocyclic Carbene Rare-Earth Metal Alkyls were synthesized for the first time.LiCH₂Si Me₃ is used as the base to remove the protons of the imidazolium saltto generate carbene ligands.The carbene prepared by the above method without separation reaction with alkyl rare earth metal and rare earth metal complexs 1-3?Ln=Sc,Y,Lu?was prepared.The complexes were characterized by nuclear magnetic resonance hydrogen spectrum,carbon spectrum,X-ray single crystal diffraction and FT-IR.The homopolymerization properties of complexes 1,2 and 3 under the activation of[Ph₃C][B?C₆F₅?₄]for?-olefins and isoprene were investigated.It is found that when the central metal is scandium,the catalytic system can catalyze the polymerization of 1-hexene and 1-ocenene.The polyolefin has a medium molecular weight and a narrow molecular weight distribution.With the increase of the length of the monomer carbon chain,the polymerization activity was slightly reduced;The complexes 1,2 and 3 were activated by[Ph3C][B?C6F5?4]as a catalyst for the polymerization of isoprene,and the catalytic system had a higher cis-1,4-selectivity.When the central metal is scandium,the catalytic activity is the highest and the cis-1,4-selectivity is the highest.In this chapter,the active species of the catalytic system are studied.It can be speculated by ¹H NMR spectrum that dicationic?[?Biso-NHC?ScCH₂SiMe₃][Ph₃C][B?C₆F₅?₄]?is the active species of the reaction system.The catalytic system of N-heterocyclic carbene scandium metal complexe was studied to catalyze the copolymerization of 1-hexene with 1,5-hexadiene and 1-hexene with1,7-octadiene.Under the dilute condition,the N-heterocyclic carbene scandium metal complex can be activated by 2 times[Ph3C][B?C6F5?4],which can catalyze the copolymerization of 1-hexene with 1,5-hexadiene.When the feed ratio of 1,5-hexane to1-hexene was from 300/700 to 700/300,the content of 1,5-hexadiene in the copolymer increased from 25.5%to 72.1%.By adjusting the feed ratio of the monomer,the content of 1,5-hexadiene in the copolymer can be regulated accurately;The catalytic system can catalyze the copolymerization of 1-hexene and 1.7-octadiene.By the structure characterization of the obtained copolymer,it is known that when the monomer concentration is 1M,1.7-octadiene is mainly cyclo-polymerization,and exists in the copolymers in the way of seven membered ring.When the monomer concentration is 0.5M,1.7-octadiene is mainly polymerized with one end of the double bond,and copolymers with vinyl groups are obtained.When the feeding ratio of 1-hexene to 1,7-octadiene from 700/300 to 300/700,the content of 1,7-octadiene in the copolymer increased from 32%to 70.6%,and the content of double bonds increased from 6.29%to 15.6%.By adjusting the feeding ratio of the monomer,the content of1,7-octadiene and double bonds in the copolymer can be regulated accurately.The functionalization of the vinyl groups in the polymer was studied in this paper.The polar group carboxyl group was introduced into the polymer by photocatalytic free radical reaction.Introduction of carboxyl showed beneficial to improving surfaceproperties of hydrophobic polyolefin.The static contact angle of water on functionalized copolymer is 103.5°,which is smaller than the contact angle of unfunctionalized polyolefin?110.4°?,indicating the improvement of hydrophilcity...