Polymerization of methyl methacrylate by iron(II) pyridinebisimine complexes

Fe(II) pyridinebisimine complexes activated with trialkylaluminium or modified methylaluminoxane (MMAO) as catalysts were employed for the polymerization of methyl methacrylate. Polymer yields, activities and polymer molecular weights as well as molecular weight distributions can be controlled over a wide range by the variation of the structures of the Fe(II) pyridinebisimine complexes and the reaction parameters such as Al/Fe molar ratio, monomer/catalyst molar ratio, monomer concentration, reaction temperature and time applied to the polymerization of methyl methacrylate. Under optimum condition, the catalytic activity of Fe(II) complex is of up to 74.5 kg(polym)/mol(Fe)h.

The synthesis and catalytic activity of poly(bis(imino)pyridyl) iron(II) metallodendrimer

The first and second generation carbosilane dendrimers with silicon hydride terminated were synthesized, and then reacted with bis(imino)pyridyl containing allyl [4-CH2==CHCH2-2,6-(Pr2C6H3N)-Pr-i==CMe(C5H3N)MeC==N(2,6-'Pr2C6H3)], in the presence of H2PtCl6 as a hydrosilylation catalyst, to afford the first and second generation carbosilane supported ligands. Complexation reactions with FeCl(2)(.)4H(2)O give rise to iron-containing carbosilane dendrimers with FeCl2 moieties bound on the periphery. The metallodendrimers were used as catalyst precursors, activated with modified methylaluminoxane, for the polymerization of ethylene. In the case of low Al/Fe molar ratio, the metallodendrimers display much higher catalytic activity towards ethylene polymerization and produce much higher molecule weight polyethylenes than the corresponding single-nuclear complex under the same conditions.

Synthesis, structure and norbornene polymerization behavior of nickel complexes bearing two beta-ketoiminato chelate ligands

A series of nickel(II) complexes bearing two nonsymmetric bidentate beta-ketoiminato chelate ligands have been prepared, and the structures of complexes [(2,6-Me2C6H3)NC(CH3)C(H)C(Ph)O](2)Ni (4a) and [(2,6-Me2C6H3)NC(CH3)C(H)C(CF3)O](2)Ni (4c) have been confirmed by X-ray crystallographic analysis. These nickel(II) complexes were investigated as catalysts for the vinylic polymerization of norbornene. Using modified methylaluminoxane (MMAO) as a cocatalyst, these complexes display very high activities and produce high molecular weight polymers. Catalytic activity of up to 1.16 x 10(4) kg/mol(Ni) .h and the viscosity-average molecular 9 weight of polymer of up to 870 kg/mol were observed. Catalyst activity, polymer yield, and polymer molecular weight could be controlled over a wide range by the variation of the reaction parameters such as Al/Ni molar ratio, norbornene/catalyst molar ratio, monomer concentration, polymerization reaction temperature and time.

Synthesis, structure and norbornene polymerization behavior of neutral palladium complexes

A series of neutral palladium(II) complexes bearing non-symmetric bidentate pyrrole-iminato or salicylaldiminato chelate ligands have been synthesized, and the structure of representative complexes (3a, 4a, and 5a) have been confirmed by X-ray crystallographic analysis. These palladium complexes have been investigated as catalysts for the polymerization of norbornene. Using modified methylaluminoxane (MMAO) as a cocatalyst, these complexes display high activities and produce vinyl-addition polynorborenes. Catalytic activity of up to 8.52 x 10(3) kg/mol(Pd) h has been observed. Wide-angle X-ray diffraction (WAXD) has been used to investigate the polymer microstructure and it has been found that they are non-crystalline.