Alkyl substituents triggered an unexpected formation of mono-and dinuclear zirconium hydrazonate complexes: synthesis,characterization and their catalytic behavior toward ethylene polymerization |
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| Authors: | Xin-E Duan Bo Yuan Rui Li Arumugam Vignesh Chantsalnyam Bariashir Zilong Li Sheng-Di Bai Yanping Ma Jian-Bin Chao Hong-Bo Tong Wen-Hua Sun |
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| Institution: | 1. School of Chemistry and Chemical Engineering, Shanxi University, Taiyuan, 030006 China;2. Key Laboratory of Engineering Plastics and Beijing National Laboratory for Molecular Sciences, Institute of Chemistry, Chinese Academy of Sciences, Beijing, 100190 China;3. Institute of Applied Chemistry, Shanxi University, Taiyuan, 030006 China |
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| Abstract: | Mononuclear zirconium complex 3a of the molecular identity Zrη2-(C4H3O)C (Et) = NNPh]Cl3(THF)2], dinuclear zirconium complexes 3b {Zrη2-(C4H3O)C(i-Pr) = NNPh]2}2(μ2-Cl)3(μ3-Cl)2Li(Et2O)] and 3c {Zrη2-(C4H3O)C(t-Bu) = NNPh]2}2Cl2(μ2-Cl)2] have been synthesized by the treatment of lithium salt of (C4H3O)C(R) = NNHPh (R = CH3CH2, 1a ; R = (CH3)2CH, 1b ; R = (CH3)3C, 1c ), with different molar ratios of anhydrous zirconium tetrachloride. Of these, complex 3b was formed with lithium adduct and no such adduct was found in complex 3c . Compound 1a and all the zirconium complexes ( 3a - 3c ) were structurally characterized by single-crystal X-ray diffraction studies. Thus, it revealed that each hydrazonato ligand acts in a strained η2-coordination fashion for the three zirconium complexes. The molecular structures of the three zirconium complexes ( 3a - 3c ) reveal the existence of intramolecular hydrogen bonding interactions. Interestingly, complexes 3a and 3b assemble into a two-dimensional network structure through intermolecular hydrogen-bonding interactions. Upon activation with methylaluminoxane (MAO), all the complexes namely 3a , 3b , and 3c exhibited moderate catalytic activities toward ethylene polymerization and produced high molecular weight polyethylene with narrow molecular weight distributions. |
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| Keywords: | ethylene polymerization hydrazonato ligand hydrogen bonding lithium salt zirconium complexes |
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