Boron trifluoride activation of ethylene oligomerization and polymerization catalysts

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• 作者：Komon ; Zachary J.A. ; Bazan ; Guillermo C. ; Fang ; Cindy ; Bu ; Xianhui
• 关键词：Ethylene polymerization ; Homogeneous catalysis ; Nickel ; Borane activation ; Branched polyethylene
• 刊名：Inorganica Chimica Acta
• 出版年：2002
• 出版时间：March 10, 2002
• 年：2002
• 卷：345
• 期：Complete
• 页码：95-102
• 全文大小：213 K

文摘

Addition of BF₃·Et₂O to {[(C₆H₅)₂PC₆H₄(μ-CO₂)-κ³P,O,O′]Ni(η¹-CH₂C₆H₅)}₂ gives [(C₆H₅)₂PC₆H₄C(Ocenter border=0 SRC=/images/glyphs/BO7.GIF>BF₃)O-κ²P,O]Ni(η³-CH₂C₆H₅) (4). The single crystal structure of 4 is consistent with substantial positive charge at the nickel atom. Addition of ethylene to solutions of 4 in toluene provides ethylene oligomers. The average molecular weight of the products is larger than that of the oligomers obtained using [(C₆H₅)₂PC₆H₄C(OB(C₆F₅)₃)O-κ²P,O]Ni(η³-CH₂C₆H₅) (1). When 2 equiv. of Et₂O·BF₃ are added to {(H₃C)C[N(2,6-(CHMe₂)₂center border=0 SRC=/images/glyphs/BO7.GIF>C₆H₃)]C(O)[N(2,6-(CHMe₂)₂center border=0 SRC=/images/glyphs/BO7.GIF>C₆H₃)]-κ²N,O}Ni(η¹-CH₂C₆H₅)(PMe₃) (5) one obtains {(H₃C)C[N(2,6-(CHMe₂)₂center border=0 SRC=/images/glyphs/BO7.GIF>C₆H₃)]C[Ocenter border=0 SRC=/images/glyphs/BO7.GIF>BF₃][N(2,6-(CHMe₂)₂center border=0 SRC=/images/glyphs/BO7.GIF>C₆H₃)]-κ²N,N′}Ni(η³-CH₂C₆H₅) (7). Two isomers of 7 are observed by NMR spectroscopy and are incorporated into the crystal lattice, as shown by X-ray diffraction studies. Polyethylene is obtained upon exposure of a solution of 7 to ethylene. Active species can also be generated in situ by addition of BF₃ gas, Et₂O·BF₃ or ^tBuMeO·BF₃ to 5.