title: Well-defined phosphino-phenolate neutral nickel(II) catalysts for efficient (co)polymerization of norbornene and ethylene.
abstract: Phosphino-phenolate neutral nickel catalysts 1-3/B(C6F5)3, without the help of any organoaluminum compound, were found to be efficient catalytic systems for norbornene polymerization and its copolymerization with norbornene derivatives. The amount of B(C6F5)3 required for achieving a high efficiency (3 equiv.) was markedly lower compared to previous reports, and high molecular weight polymers were obtained (>10(6) g mol(-1)). Efficient incorporation of polar monomers NBC, NBA, and NBM was also achieved in a controllable fashion, yielding high molecular weight copolymers. Catalysts 1-3 were highly active for ethylene polymerization as single component catalysts, with an activity of up to 10(7) g molNi(-1) h(-1), and catalyst 3 was more readily initiated at lower temperature. Catalysts 1-3 were also efficient in incorporating norbornene (up to 30%) into the polyethylene backbone. Bisligated phosphino-phenolate nickel complex 4 and salicylaldimine complex 5 were also studied for comparison, which further verified the unique performance of catalysts 1-3. Preliminary NMR analyses were conducted to explore the norbornene polymerization mechanism.
authors: State Key Laboratory of Polymer Physics and Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022, China. muhongliang@ciac.ac.cn.
authors: Yan-Ping
authors: YP
authors: Zhang
authors: Wei-Wei
authors: WW
authors: Li
authors: Bai-Xiang
authors: BX
authors: Li
authors: Hong-Liang
authors: HL
authors: Mu
authors: Yue-Sheng
authors: YS
authors: Li