Retro-Brook rearrangement induces the formation of an octahedral nickel(benzamidinate) complex; synthesis, structure and catalytic activity |
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Authors: | Elza Nelkenbaum |
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Institution: | Department of Chemistry and Institute of Catalysis Science and Technology, Technion - Israel Institute of Technology, Kyriat Hatechnion, Haifa 32000, Israel |
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Abstract: | The neutral octahedral nickel complex (PhC(NSiMe3)NC(Ph) CHSiMe3)Ni(acac)(TMEDA) (7), has been synthesized and characterized including X-ray diffraction analysis. The complex was formed by the reaction of Ni(acac)2(TMEDA) with the lithium salt of the corresponding β-diketiminate ligand. The formation of the benzamidinate motif from the corresponding β-diketiminate is a consequence of a retro-Brook isomerization that is operative only at the nickel centre. A plausible mechanism for the metal mediated isomerization is proposed. When complex 7 was activated with MAO it showed a good catalytic activity for the addition polymerization of norbornene. Furthermore, this catalytic system has been found to oligomerize ethylene to a mixture of butenes and hexenes with a high turnover frequency, η = 29,300 h−1, when the reaction is performed in dichloromethane. |
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Keywords: | Diketiminates Polymerization Retro brook isomerization Ethylene oligomerization Nickel X-ray structure |
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