Studies On Synthesis Of Novel N,N Bidentate Nickel Complexes And Their Activity In Ethylene Reactivity

This dissertation focuses on designing and synthesis of N-(2-Substituted-5,6,7-trihydroquinolin-8-ylidene)arylamino-based N,N-Ni(â…¡) complexes and their application on ethylene oligomerization/polymerization. All those nickel complexes were synthesized by high-efficiency one-pot reaction, meanswhile, the raw material are not very expensive and can be obtained conveniently. Some respective complexes were determined bu X-ray diffraction, the molecular structures showed that the coordinate number for the nickel center varied according to the bulkiness of the substitents in the ligands. The catalytic behaviors of those complexes were invested and discussed in detail with various cocatalysts,reaction parameters (such as molar ratio of Al/Ni, reaction temperature and time) and the nature of different ligands to elucidate their influence on the catalytic activity for ethylene polymerization. In the precence of EASC, all title complexes showed high activity in ethylene oligomerization with producing butanes and hexenes in high alpha selectivity (>99%). Three main parts are included in this dissertation:Partâ… : The progress of catalysts used in polymerization and/or oligomerization of ethylene is summarized, especially for nickel complexes.Partâ…¡: The tentative synthesis of N-(2-Substituted-5,6,7-trihydroquinolin- 8-ylidene)arylamino. However, the condensation of ketone with aniline produces imine as well as an isomer (amine). Hence, one-pot reaction was utilized to proceed this work. A series of N-(2-Substituted-5,6,7-trihydroquinolin-8-ylidene)arylaminonickel dichlorides was synthesized by one-pot stoichiometric reaction at a relatively high yield. All nickel complexes were characterized by elemental and spectroscopic analysis. The molecular structures of representative nickel complexes, determined by the single-crystal X-ray diffraction, indicate the different coordination numbers around nickel either four with more bulky ligands or five with less bulky ligands.Partâ…¢: Upon treatment with ethylaluminium sesquichloride (Et₃Al₂Cl₃), all those nickel complexes show high activity toward ethylene oligomerization with optimizing the reaction conditions (reaction temperature and time), Al/Ni molar ratio as well as the nature of the ligands.