Solvent and co-catalyst dependent pyrazolylpyridinamine and pyrazolylpyrroleamine nickel(II) catalyzed oligomerization and polymerization of ethylene
摘要:
The pyrazolylamine ligands, 2-(3,5-dimethy1-1H-pyrazol-1-y1)-N-(pyridin-2-ylmethyl)ethanamine (L1a), 2 -(3,5 -d i-tert-butyl-1 H-pyrazol-1-y1)-N-(pyridin-2-ylmethyl)ethan-amine (L2a), 2-(3,5-dimethyl-pyrazol-1-yl)-ethyl-(1H-pyrrol-2-ylmethyl)-amine (L3a), 2-(3,5-di-tert-butyl-pyrazol-1-y1)-ethyl-(1H-pyrrol-2-ylmethyl)-amine (L4a), were prepared by reducing the corresponding imine compounds L1-L4. L1a-L4a were then reacted with [NiBr2(DME)] to form the nickel complexes, [NiBr2(L1a)] (1), [NiBr2(L2a)] (2), [NiBr2(L3a)] (3) and [NiBr2(L4a)] (4) in high yields.When activated with aluminum co-catalysts, all four nickel complexes were able to catalyze the oligomerization or polymerization of ethylene; but the products of these reactions were co-catalyst and solvent dependent. With EtAlCl2 as co-catalyst and in toluene, butene and hexene were formed, which subsequently alkylated the solvent selectively to butyl-, dibutyl- and tri-butyltoluene. The same catalysts in chlorobenzene produced butene, hexene and highly branched polyethylene. Changing the co-catalysts to MAO and with toluene as solvent, complexes 2 and 3 catalyzed the polymerization of ethylene to high molecular weight (447,300 Da) linear high density polyethylene (ca T-m = 135.5 degrees C); with polydispersity indices ranging from 1.63 to 2.51. (C) 2013 Elsevier B.V. All rights reserved.
The pyrazolylamine ligands, 2-(3,5-dimethy1-1H-pyrazol-1-y1)-N-(pyridin-2-ylmethyl)ethanamine (L1a), 2 -(3,5 -d i-tert-butyl-1 H-pyrazol-1-y1)-N-(pyridin-2-ylmethyl)ethan-amine (L2a), 2-(3,5-dimethyl-pyrazol-1-yl)-ethyl-(1H-pyrrol-2-ylmethyl)-amine (L3a), 2-(3,5-di-tert-butyl-pyrazol-1-y1)-ethyl-(1H-pyrrol-2-ylmethyl)-amine (L4a), were prepared by reducing the corresponding imine compounds L1-L4. L1a-L4a were then reacted with [NiBr2(DME)] to form the nickel complexes, [NiBr2(L1a)] (1), [NiBr2(L2a)] (2), [NiBr2(L3a)] (3) and [NiBr2(L4a)] (4) in high yields.When activated with aluminum co-catalysts, all four nickel complexes were able to catalyze the oligomerization or polymerization of ethylene; but the products of these reactions were co-catalyst and solvent dependent. With EtAlCl2 as co-catalyst and in toluene, butene and hexene were formed, which subsequently alkylated the solvent selectively to butyl-, dibutyl- and tri-butyltoluene. The same catalysts in chlorobenzene produced butene, hexene and highly branched polyethylene. Changing the co-catalysts to MAO and with toluene as solvent, complexes 2 and 3 catalyzed the polymerization of ethylene to high molecular weight (447,300 Da) linear high density polyethylene (ca T-m = 135.5 degrees C); with polydispersity indices ranging from 1.63 to 2.51. (C) 2013 Elsevier B.V. All rights reserved.
Ethylene and Styrene Carbon Monoxide Copolymerization Catalyzed by Pyrazolyl Palladium(II) Complexes
作者:Collins Obuah、Michael K. Ainooson、Sibulele Boltina、Ilia A. Guzei、Kyoko Nozaki、James Darkwa
DOI:10.1021/om300798y
日期:2013.2.25
[PdCl(Me)(cod)] gave the corresponding palladium(II) complexes [PdCl(Me)(L)] (where L = L1 (1a), L2 (2a), L3 (3a), L4 (4a), L5 (5a), L6 (6a)) in very good yields. The pyridylimine ligands L1 and L2 were found to coordinate via the imine and pyridine nitrogen atoms, while the thienylimine ligands L3–L6 coordinate via imine and pyrazolyl nitrogen atoms to the palladium. The cationic complexes [Pd(Me)(A)]+