Study On Synthesis,Characterization And Catalytic Performance Of New Metallocene And Non-metallocene Catalysts

Polyolefin is closely related to our life as an important product.The rapid development of polyolefin industry greatly promotes the development and progress of various fields.And the development and progress of polyolefin catalyst is the key to the development of polyolefin industry,its development mainly includes Ziegler-Natta catalyst,Phillips catalyst,metallocene catalysts and non-metallocene catalysts.Among them,metallocene catalysts and non-metallocene catalysts are dominant in the polyolefin industry because of their simple synthesis and high catalytic efficiency.At present,many researches are devoted to the synthesis,characterization and catalytic properties of new metallocene and non-metallocene catalysts.(1)Of the monocyclopentadienyl Cr(III)complexes,the so called constrained-geometry monocyclopentadienyl Cr(III)complexes with a chelating side arm cont aining a nitrogen,oxygen,sulphur or phosphorus donor have attracted particular attention due to their structural features,and have been reported to be efficient c atalyst precursors for ethylene homo-and co-polymerization.A series of new hal f-sandwich secondary amine-coordinated dichlorochromium complexes chelated by 2-(tetramethylcyclopentadienyl)benzylamine ligands,2-Me4CpC6H4CH2(R)NHCrCl2[R=iPr(1),Cy(2),Ph(3),4-MePh(4),2,6-Me2Ph(5),2,6-Et2Ph(6)]have be en synthesized from the reactions of CrCl3(THF)3 with the dilithium salts of the corresponding ligands in THW,followed by addition of 1/2 eq of H2O to the rea ction mixtures.The isolated yields of the chromium complexes were found to in crease with the increase in the amount of H2O introduced and reach the highest values(66-76%)when 1/2 eq of H2O was added.Attempts to isolate the 2-(tetr amethylcyclopentadienyl)benzylamidochromium complexes,2-Me4CpC6H4CH2(R)NC rCl,were not successful.The new dichlorochromium complexes were characterize d by IR,1H NMR,EPR,UV/Vis spectroscopies,and elemental analyses,and the molecular structures of complexes 1,5 and 6 were determined by X-ray crystall ography.The X-ray crystallographic analysis reveals that these chromium comple xes possess a three-legged piano-stool geometry with the amine N atom in a mit ered six-membered chelating ring and the two chloride atoms as the legs.Upon activation with AIR3 and Ph3CB(C6F5)4,complexes 1-6 exhibit reasonable catalyti c activity for ethylene polymerization and copolymerization with 1-hexene,produ cing polyethylenes with moderate to high molecular weights and poly(ethylene-co-1-hexene)s with moderate comonomer incorporation which are typical linear low-density polyethylene(LLDPE).Complex 4 was found to show higher catalytic ac tivity for ethylene homo-and co-polymerization than other complexes under simil ar conditions,while complex 3 produced poly(ethylene-co-l-hexene)s with the hig hest comonomer incorporation(2)In recent years,constrained geometry catalysts containing oxygen atoms have been developed due to their unique structural characteristics and excellent catalytic activity.A series of new half-sandwich titanium complexes[?5:?1-2-Cp'-4-tBu-6-R-C6H2O]TiCl2[R=tBu,Cp'=Flu(7),R=CPhMe2,Cp'=CpMe4(8),R=CPh2Me,Cp'=CpMe4(9),R=C(p-Tolyl)3,Cp'=CpMe4(10)]were synthesized from reactions of TiCl4 either directly with corresponding free ligands,2-Cp'-4-'Bu-6-R-C6H2OH[R=CPhMe2,Cp'=CpMe4(H2L8),R=CPh2Me,Cp'=CpMe4(H2L9),R=C(p-Tolyl)3,Cp'=CpMe4(H2LIO)],or with the dilithium salt of the free ligand 2-Cp'H-4-tBu-6-R-C6H2OH[R=tBu,Cp'=Flu(H2L7)]in toluene.These new titanium complexes were fully characterized by 1H and 13C NMR spectroscopy and elemental analyses,and the molecular structures of complexes 7 and 9 were determined by single-crystal X-ray crystallography.Upon activation with Al'Bu3 and Ph3CB(C6Fs)4,these complexes exhibit high catalytic activity for ethylene polymerization as well as ethylene/1-hexene copolymerization with good comonomer incorporation ability.It was found that the bulky substituents at the ortho position of the phenoxy group in the ligands of these complexes apparently influences the molecular weight and the microstructure of the resultant polymers.Complex 10 was found to show higher catalytic activity for ethylene homopolymerization and copolymerization than other complexes under similar conditions,and complex 10 produced poly(ethylene-co-1-hexene)s with the highest comonomer incorporation.(3)A new ortho-dimethylaminomethylphenyl-tetramethylcyclopentadienyl ligand C5Me4H-C6H4-o-CH2NMe2(HL11)and a series of rare-earth metal complexes bearing this ligand were synthesized.Of these complexes,two binuclear alkyl complexes[(C5Me4-C6H4-o-CH2N(Me)CH2-?)Ln(CH2SiMe3)]2(Ln=Sc(11a),Y(11b))were obtained from the alkane elimination reaction of the free ligand with Ln(CH2SiMe3)3(THF)2,followed by an intramolecular C-H activation process of a NMe group in the ligand with a CH2SiMe3 group,two binuclear dichloro complexes(C5Me4-C6H4-o-CH2NMe2)2Y2Cl4[LiCl(THF)2](11c)and[(C5Me4-C6H4-o-CH2NMe2)LuCl(?-Cl)]2(11d)were synthesized by the reaction of anhydrous yttrium or lutecium trichloride with the lithium salt of the ligand LiL,while the binuclear bis(borohydrido)complexes[(C5Me4-C6H4-o-CH2NMe2)Ln(?-BH4)BH4]2(Ln=Sm(11e),Nd(11f))were synthesized by the reaction of Ln(BH4)3(THF)3(Ln=Sm,Nd)with the lithium salt of the ligand.The molecular structures of all complexes 11a,11b,11c,11d,11e and 11f were determined by single-crystal X-ray crystallography.Upon activation with AlR3/Ph3CB(C6F5)4,MAO or MMAO,the binuclear alkyl complexes 11a and 11b show good catalytic activity for isoprene cis-1,4 enriched regioselective polymerization and moderate catalytic activity for 1-hexene polymerization.Complexes 11e and 11f were studied as catalysts for methyl methacrylate polymerization reaction under different conditions and were found to display moderate to high catalytic activity.(4)The group 4 transition metal complexes bearing a tridentate or tetradentate bridged bisphenolato chelating ligand with one or two bridging O or S atom(s)have attracted attention of several research groups due to their unique structural characteristics.A number of new sulfur-bridged tridentate[OSO]bisphenolato-based ligand precursors S(2-CH2-4-tBu-6-R-C6H2OH)2[R=CMe3(H2L12),CMe2Ph(H2L13),CMePh2(H2L14),CPh3(H2L15),C(p-Tol)3(H2L16)]were synthesized by reactions of Na2S·9H2O with 2 eq.of corresponding 2-(bromomethyl)-4-(tert-butyl)-6-R-phenol.Their neutral titanium complexes[S(2-CH2-4-tBu-6-R-C6H2O)2]TiCl2[R=CMe3(12),CMe2Ph(13),CMePh2(14),CPh3(15),C(p-Tol)3(16)]were synthesized in high yields by direct HCl-elimination reactions of TiCl4 with the corresponding ligand precursors in toluene.Ionic titanium complexes[NHEt3][S(2-CH2-4-tBu-6-R-C6H2O)2TiCl3][R=CMe3(17),CMePh2(18)]and[NH2Et2][S(2-CH2-4-'Bu-6-R-C6H2O)2TiCl3][R=CMe3(19),CMePh2(20)]were obtained in high yields from the reactions of TiCl4 with the corresponding ligand precursors in the presence of 2 eq.of triethylamine or diethylamine.Neutral zirconium complexes[S(2-CH2-4-tBu-6-R-C6H2O)2]ZrCl2(THF)[R=CMe2Ph(21·THW),CMePh2(22·THF)]were synthesized by reactions of ZrCl4 with 1 eq.of dilithium salt of the corresponding ligand precursors Li2L in THF.The new titanium and zirconium complexes were characterized by 1H and 13C NMR,IR and elemental analyses.The molecular structures of complexes 15,17 and 21.THF were determined by single-crystal X-ray diffraction analysis.The X-ray crystallography analysis reveals that titanium complex 15 has a five-coordinating environment surrounding the central metal atom,while the titanium complex 17 and the THF-solvated zirconium complex 21.THF possess a six-coordinating pseudo-octahedral environment around the central metal atom.Upon activation with MAO or AliBu3/Ph3CB(C6F5)4,all these titanium and zirconium complexes exhibit moderate to high catalytic activities for ethylene polymerization and ethylene/1-hexene copolymerization with moderate to high comonomer incorporation,and the ionic titanium complexes 17,18,19 and 20 show lower catalytic activity than their corresponding neutral complexes under similar conditions.