1100360-53-9Relevant academic research and scientific papers
Elaborate Tuning in Ligand Makes a Big Difference in Catalytic Performance: Bulky Nickel Catalysts for (Co)polymerization of Ethylene with Promising Vinyl Polar Monomers
Zhang, Yanping,Mu, Hongliang,Wang, Xuling,Pan, Li,Li, Yuesheng
, p. 2329 - 2340 (2019)
To reveal effect of electronic or steric modification of phosphino-phenolate nickel complex for preparing optimized catalysts, we take elaborated studies on structure-performance relationship by finely modifying substituents on ortho-phenoxy position or phosphorus moiety of this catalyst. It reveals that these newly synthesized complexes are thermally robust, and exhibits very high activity (up to 107 g molNi?1 h?1) in ethylene polymerization even at 120 °C. Associated with stoichiometric experiments, experimental results prove that nickel complexes bearing electron-withdrawing substituents on ortho-phenoxy position or electron-donating substituents on phosphorus atom show higher activity than contrastive catalysts toward ethylene polymerization and ethylene–methyl acrylate (MA) copolymerization. Among these catalysts, 3 g bearing a strong electron-withdrawing substituent on ortho-phenoxy position exhibits the highest activity, and produces copolymers with the highest molecular weight and analogous MA incorporation. Various challenging polar vinyl monomers, like polyethylene glycol monomethyl ether acrylate, can be efficiently copolymerized with ethylene.
Synthesis and characterization of novel half-metallocene-type group IV complexes containing phosphine oxide - Phenolate chelating ligands and their application to ethylene polymerization
Liu, Jing-Yu,Liu, San-Rong,Li, Bai-Xiang,Li, Yan-Guo,Li, Yue-Sheng
body text, p. 4052 - 4059 (2011/10/03)
A series of novel half-metallocene-type group IV metal complexes containing phosphine oxide-phenolate chelating ligands of type CpMCl2[O-2R 1-4R2-6(Ph2P=O)C6H2] (Cp = C5H5, M = Ti, 2a: R1 = R2 = H; 2b: R1 = Ph, R2 = H; 2c: R1 = tBu, R2 = H; 2d: R1 = R2 = tBu; M = Zr, 3b: R1 = Ph, R2 = H; 3c: R1 = tBu, R2 = H; 3d, R1 = R2 = tBu) have been synthesized in high yields (60-76%) from CpMCl3 (M = Ti, Zr) with 1.0 equiv of 2R1-4R2-6(Ph2P=O)C 6H2OH in THF and in the presence of triethylamine, and the complexes were identified by NMR and mass spectra as well as elemental analysis. Structures for 2a-d and 3d were further confirmed by X-ray crystallography. Complexes 2a-d adopt a five-coordinate, distorted square-pyramidal geometry around the titanium center. Complex 3d has a six-coordinate, distorted octahedral geometry around the zirconium center, in which the equatorial positions are occupied by oxygen atoms of the chelating phosphine oxide-phenolate ligand and two chlorine atoms. The cyclopentadienyl ring and the oxygen atom of the THF molecule are coordinated on the axial position. When activated by modified methylaluminoxane, all complexes exhibited moderate to high activities toward ethylene polymerization, giving high molecular weight polymer with a unimodal molecular weight distribution. The substituents on ligands and the metal center as well as the reaction conditions have a profound effect on the polymerization. It should be noted that zirconium complexes 3b-d displayed notable ethylene polymerization activity even at high temperature (75 C). Moreover, using Ph3CB(C6F 5)4/i-Bu3Al in place of MMAO as a cocatalyst, 3b-d also generate high molecular weight polymer with high efficiency under the same conditions.
