Synthesis And Characterization Of Nickel And Palladium Complexes For Olefin Polymerization

The thesis consists of four chapters as follows:Chapter I: ReviewsPolyolefin is a very important kind of polymer for its wide use in various industries,and its production technology represents the development level of a country’spetrochemical industry to a large degree. The development core of the polyolefinmaterials is the R&D of the new olefin polymerization catalyst, thus, the design andsynthesis of novel olefin polymerization catalyst has always been a research focus of thepolymer disciplinary.In the paper we elucidated the latest progresses of a series of late transition metalcatalyst systems incorporating α-diimine ligands used in olefin polymerization, ethyleneoligomerization and copolymerization of olefins with polar monomers. The effects ofdifferent late transition metal ion, α-diimine backone and the ligand on it, differentpolymerization conditions （temperature and pressure） on the catalysts polymerizationactivity, branching degree, molecular weight and its distribution of the polymer and theproperties of the polymer produces were elucidated systematically.Chapter Ⅱ: New Chiral α-Diimine Nickel（Ⅱ） Complexes Bearingortho-sec-Phenethyl Groups for Ethylene PolymerizationA series of new α-Diimine Nickel（Ⅱ） Catalysts bearing bulky chiral sec-phenethylgroups, have been synthesized and characterized. The molecular structure ofrepresentative chiral ligand, bis[N,N′-（4-methyl-2,6-di-sec-phenethylphenyl）imino]-1,2-dimethylethane （S,R,S,R）-1c and chiral complexes,{bis[N,N′-（4-methyl-2-sec-phenethylphenyl）imino]-2,3-butadiene}dibromonickel （S,R）-2a and bis{bis[N,N′-（4-methyl-2-sec-phenethylphenyl）imino]-2,3-butadiene}dibromonickel（S,S,S,S/R,R,R,R）-2b, were confirmed by X-ray crystallographic analysis. Complex（S,R,S,R）-2c bearing two chiral sec-phenethyl groups in the ortho-aryl position and amethyl group in the para-aryl position, activated by diethylaluminum chloride （DEAC）,showed highly catalytic activity for the polymerization of ethylene [4.12×10⁶gPE/（mol Ni·h·bar）], and produced highly branched polyethylenes under lowethylene pressure （branching degree:104,118and126branches/1000C at20,40and60°C, respectively）. Chiral20-electron bis-α-diimine Ni（Ⅱ） complex （S,S,S,S/R,R,R,R）-2b also exhibited high activity toward ethylene polymerization [1.71×10⁶g PE/（mol Ni·h·bar）]. The type and amount of branches of the polyethylenesobtained were determined by1H NMR and13C NMR.Chapter ⅡI: Syndiotactic polymerization of methyl methacrylate （MMA） by newα-Diimine Nickel （Ⅱ） Catalysts containing Naphthyl Moieties/DEAC SystemsFive new α-diimine nickel（Ⅱ） complexes containing naphthyl groups,bis{bis[N,N′-（1-naphthyl）imino]-1,2-dimethylethane}dibromonickel2a,bis{bis[N,N′-（2-methyl-1-naphthyl）imino]-1,2-dimethylethane}dibromonickel2b,bis{bis[N,N′-（2-（1-phenylethyl）naphthaly）imino]-1,2-dimethylethane}dibromonickel2c,bis{bis[N,N′-（2-methyl-1-naphthyl）imino]acenaphthene}dibromonickel2d andbis{bis[N,N′-（2-naphthyl）imino]-1,2-dimethylethane}dibromonickel2e, weresynthesized and characterized. The molecular structure of complex2c,2d and ligand1b-e were submitted for X-ray diffraction analysis. The X-ray structure of complex2c,2d features a pseudo-tetrahedral geometry about the nickel atom. These complexes,activated by diethylaluminum chloride （DEAC） were tested in the polymerization ofolefins under mild conditions. Based on the α-diimine nickel catalyst containingnaphthyl moieties, chiral nickel catalyst2c yielded PMMA with higher syndiotacticitythan achiral catalysts under the same experimental conditions.Chapter IV: Teraryl-substituted α-diimine ligand-based Nickel（Ⅱ） andPalladium（Ⅱ） olefin polymerization catalysts: Synthesis, Characterization, andApplicationA series of Ni（Ⅱ） and Pd（Ⅱ） α-diimine olefin polymerization catalysts bearing2,6-diphenyl groups [ArN=C（Nap）C=NAr] NiBr₂（Nap=1,8-naphthdiyl, Ar=4-F-2,6-Ph₂C₆H₃,4a; Ar=4-Cl-2,6-Ph₂C₆H₃,4b; Ar=4-Me-2,6-Ph₂C₆H₃,4c; Ar=4-n-Bu-2,6-Ph₂C₆H₃,4d）,[ArN=C（Nap）C=NAr] PdCl₂（Nap=1,8-naphthdiyl, Ar=4-F-2,6-Ph₂C₆H₃,5a; Ar=4-Cl-2,6-Ph₂C₆H₃,5b; Ar=4-Me-2,6-Ph₂C₆H₃,5c） have been synthesized,characterized. Suitable crystals4a,4b and5a were submitted for X-ray diffractionanalysis. A geometry model was developed to describe the orientation of ligandfragments around the Ni（Ⅱ） and Pd（Ⅱ） center that influence the polymer microstructure.These complexes, activated by diethylaluminum chloride （DEAC） were tested in thepolymerization of olefin under mild conditions. Complex4a,4b and5a bearing 2,6-diphenyl and strong electron-withdrawing groups, activated by diethylaluminumchloride （DEAC） shows highly catalytic activity for the polymerization of ethylene andproduced dendritic polyethylene. The polymerization results indicate the possibility ofprecise microstructure control depending on the particular complex substitution.