Nickel(II) complexes with mono(imino)pyrrole ligands: preparation, structure and ethylene polymerization behavior
A series of unsymmetrical mono(imine)pyrroles (L1–L3) were synthesized by microwave irradiation from 2-acetylpyrrole and a series of dimethylanilines with two methyl groups at different positions on the aniline ring. A simplified synthetic method was initiated to prepare the corresponding nickel complexes NiL2 (1–3) with direct condensation of mono(imine)pyrrole and nickel chloride. The compounds were determined using a suite of techniques (i.e. 1H NMR, 13C NMR, IR, EA, MS). L1–L3 and 3 were further characterized by X-ray crystal diffraction. The structure of 3 showed that the ligand chelated to nickel with 2 : 1 M ratio, in spite of a 1 : 1 rate of charge. Application of 1–3 in ethylene polymerization indicated that mono(imino)pyrrole nickel complexes showed low activities. The polymerization reaction time and temperature, as well as the ligand structure, influenced the catalytic performance to some extent. Experimental data showed higher activity as –CH3 on the aniline ring is closer to the imine group.
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Document Type: Research Article
Affiliations: 1: The College of Chemistry and Chemical Engineering, Xi’an Shiyou University, Xi'an, China 2: Changzheng Engineering Co., Ltd, Lanzhou Branch, Lanzhou, China
Publication date: December 2, 2015