title: Ring-tension adjusted ethylene polymerization by aryliminocycloheptapyridyl nickel complexes.
abstract: The stoichiometric reactions of 5,6,7,8-tetrahydrocycloheptapyridin-9-one (cycloheptapyridin-9-one) with various anilines lead to corresponding mixtures of 9-aryliminocycloheptapyridine and the isomeric 9-arylamino-5,6,7-trihydrocycloheptapyridine derivatives; these compounds further reacted with nickel dichloride to form 9-aryliminocycloheptapyridyl nickel chlorides, respectively. The new organic compounds were analyzed by the NMR measurements, and all the organic and complex compounds were characterized by the FT-IR spectroscopy and elemental analysis. In addition, the molecular structures of representative nickel complexes and , determined by means of single-crystal X-ray diffraction, were found to be binuclear dimers with distorted square-pyramidal geometry around the nickel centers. On activation with either ethylaluminium sesquichloride (Et3Al2Cl3) or methylaluminoxane (MAO), all nickel complex pre-catalysts exhibited high activities of up to 7.80 × 10(6) g PE mol(-1) (Ni) h(-1) toward ethylene polymerization and produced highly branched polyethylenes in narrow polydispersity. The title nickel complexes showed comparable activities with 8-arylimino-5,6,7-trihydroquinolyl nickel analogues; whilst both exhibited higher activities than did the 2-iminopyridyl nickel analogues due to the enhancement of the ring-tension of cyclic-fused pyridine derivatives.
authors.affiliation: College of Chemical Engineering, Zhejiang University of Technology, Hangzhou 310014, China.
authors.forename: Fang
authors.initials: F
authors.lastname: Huang
authors.forename: Zelin
authors.initials: Z
authors.lastname: Sun
authors.forename: Shizhen
authors.initials: S
authors.lastname: Du
authors.forename: Erlin
authors.initials: E
authors.lastname: Yue
authors.forename: Junjun
authors.initials: J
authors.lastname: Ba
authors.forename: Xinquan
authors.initials: X
authors.lastname: Hu
authors.forename: Tongling
authors.initials: T
authors.lastname: Liang
authors.forename: Griselda B
authors.initials: GB
authors.lastname: Galland
authors.forename: Wen-Hua
authors.initials: WH
authors.lastname: Sun