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Norbornene Polymerization (norbornene + polymerization)
Selected AbstractsStable Nickel Catalysts for Fast Norbornene Polymerization: Tuning ReactivityEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 19 2005Juan A. Casares Abstract The air-stable complexes trans -[Ni(C6Cl2F3)2L2] (L = SbPh3, 1; AsPh3, 2; AsCyPh2, 3; AsMePh2, 4; PPh3, 5) have been synthesized by arylation of [NiBr2(dme)] (dme = 1,2-dimethoxyethane) in the presence of the corresponding ligand L (for compounds 1,4) or by ligand substitution starting from 1 (for compound 5). The structures of 1, 2, and 5 have been determined by X-ray diffraction and show an almost perfect square-planar geometry in all cases. Their catalytic activity in insertion polymerization of norbornene have been tested showing a strong dependence of the yield and molecular mass of the polymer on the ligand used and the solvent. High yield and high molecular mass values are obtained using complexes with ligands easy to displace from NiII (SbPh3 is the best) and noncoordinating solvents. Complexes 1,3 are suggested as convenient bench-catalysts to have available in the lab. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005) [source] Nickel Complexes and Cobalt Coordination Polymers with Organochalcogen (S, Se) Ligands Bearing an N -Methylimidazole Moiety: Syntheses, Structures, and Properties,EUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 26 2008Wei-Guo Jia Abstract The organochalcogen ligands (S, Se) derived from 3-methylimidazole-2-thione/selone groups mbit (2a), mbis (2b), ebit (2c), and ebis (2d) [mbit = 1,1,-methylenebis(1,3-dihydro-3-methyl-2H -imidazole-2-thione), mbis = 1,1,-methylenebis(1,3-dihydro-3-methyl-2H -imidazole-2-selone), ebit = 1,1,-(1,2-ethanediyl)bis(1,3-dihydro-3-methyl-1H -imidazole-2-thione), ebis = 1,1,-(1,2-ethanediyl)bis(1,3-dihydro-3-methyl-1H -imidazole-2-selone)] were synthesized and characterized. Mononuclear NiII complexes NiBr2mbit (3a), NiBr2mbis (3b), NiBr2ebit (3c), and NiBr2ebis (3d) were obtained by the reactions of Ni(PPh3)2Br2 with 2a, 2b, 2c, and 2d, respectively. However, when the corresponding ligands 2a, 2b, 2c, and 2d were treated with CoCl2 in thf solution CoII 1D coordination polymers (CoCl2mbit)n (4a), (CoCl2mbis)n (4b), (CoCl2ebit)n (4c), and (CoCl2ebis)n (4d) were obtained. All compounds were fully characterized by IR spectroscopy and elemental analysis. The crystal structures of 2c, 3a, 3b, 3c, 4a, 4b, and 4c were determined by X-ray crystallography. The local geometry around the nickel atom in complexes 3a,c was distorted tetrahedron with coordinated S(Se) and two Br atoms, and the organochalcogen ligands form an eight- or a nine-membered ring with the nickel atom included. The cobalt atom coordination polymers 4a and 4b coexist as left-handed and right-handed helical chains, but 4c formed a zigzag chain with a CH3CN solvent molecule taken up in the channel structure. After activation with methylaluminoxane (MAO), the nickel complexes exhibited high activities for addition polymerization of norbornene (1.42,×,108 g,PNBmol,1,Nih,1 for 3a). The effects of the Al/Ni ratio, reaction temperature, and reaction time to norbornene polymerization were also investigated.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008) [source] Homo- and copolymerization of ethylene and norbornene with bis(,-diketiminato) titanium complexes activated with methylaluminoxaneJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 1 2008Yongfei Li Abstract Homo- and copolymerization of ethylene and norbornene were investigated with bis(,-diketiminato) titanium complexes [ArNC(CR3)CHC(CR3)NAr]2TiCl2 (R = F, Ar = 2,6-diisopropylphenyl 2a; R = F, Ar = 2,6-dimethylphenyl 2b; R = H, Ar = 2,6-diisopropylphenyl 2c; R = H, Ar = 2,6-dimethylphenyl 2d) in the presence of methylaluminoxane (MAO). The influence of steric and electric effects of complexes on catalytic activity was evaluated. With MAO as cocatalyst, complexes 2a,d are moderately active catalysts for ethylene polymerization producing high-molecular weight polyethylenes bearing linear structures, but low active catalysts for norbornene polymerization. Moreover, 2a,d are also active ethylene,norbornene (E,N) copolymerization catalysts. The incorporation of norbornene in the E,N copolymer could be controlled by varying the charged norbornene. 13C NMR analyses showed the microstructures of the E,N copolymers were predominantly alternated and isolated norbornene units in copolymer, dyad, and triad sequences of norbornene were detected in the E,N copolymers with high incorporated content of norbornene. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 93,101, 2008 [source] Vinylic and ring-opening metathesis polymerization of norbornene with bis(,-ketoamine) cobalt complexes,JOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 22 2005Feng Bao Abstract Cobalt complexes 1,4 bearing N,O -chelate ligands based on condensation products of 1-phenyl-3-methyl-4-benzoyl-5-pyrazolone with aniline, o -methylaniline, ,-naphthylamine, and p -nitroaniline, respectively, were synthesized, and the structures of 1 and 4 were characterized by single-crystal X-ray diffraction analyses. The bis(,-ketoamine) cobalt complexes could act as moderately active catalyst precursors for norbornene polymerization with the activation of methylaluminoxane. This catalytic reaction proceeded mainly through a vinyl-type polymerization mechanism. 1H NMR and IR showed that in all cases, a small amount of double bonds raised from ring-opening metathesis polymerization (ROMP) was present in the polymerization products. The variation of the polymerization conditions affected the ROMP unit ratio in the polynorbornenes. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 5535,5544, 2005 [source] Nickel(II) complexes bearing pyrazolylimine ligand: synthesis, structure, and catalytic properties for vinyl-type polymerization of norborneneAPPLIED ORGANOMETALLIC CHEMISTRY, Issue 4 2010Yuan-yuan Wang Abstract Two nickel(II) complexes of {2-[C3HN2(R1)2 -3,5]}[C(R2)N(C6H3iPr2 -2,6)]NiBr2 (complex 1: R1 = CH3, R2 = 2,4,6-trimethylphenyl; complex 2: R1 = R2 = Ph) were synthesized and characterized. The solid-state structure of complex 1 has been confirmed by X-ray single-crystal analysis. Activated by methylaluminoxane (MAO), complexes 1 and 2 are capable of catalyzing the polymerization of norbornene with moderate activities [up to 10.56 × 105 gPNBE (mol Ni h),1] with high molecular weights (Mw,13.56 × 105 g mol,1) and molecular weight distributions were around 2. The influences of polymerization parameters such as reaction temperature and Al,Ni molar ratio on catalytic activity and molecular weight of the polynorbornene were investigated in detail. The obtained polynorbornenes were characterized by means of 1H-NMR and FTIR techniques. The analytical results of polymer structures indicated that the norbornene polymerization is vinyl-type polymerization rather than ROMP. Copyright © 2009 John Wiley & Sons, Ltd. [source] | ||||||||||