Nickel(ii) complexes bearing 4,5-bis(arylimino)pyrenylidenes: synthesis, characterization, and ethylene polymerization behaviour (original) (raw)

2013, Dalton Transactions

A series of 1,2-bis(arylimino)acenaphthylidenes (L1-L5) and their corresponding 4,4'-methylenebis-(1-(2,6-diisopropylphenylimino)-2-(arylimino)acenaphthylene) derivatives (L6-L10) were synthesized and used to form mono-nuclear nickel bromides LnNiBr 2 (n = 1-5, Ni1-Ni5) and bi-nuclear nickel halides LnNi 2 X 4 (n = 6-10: X = Br, Ni2-1-Ni2-5; n = 4, X = Cl, Ni2-6). All the organic compounds were fully characterized by FT-IR spectra, NMR measurements and elemental analysis. The nickel complexes were characterized by FT-IR spectra and elemental analysis and the molecular structures of the representative complexes Ni1, Ni2-1 and Ni2-3 were confirmed by single-crystal X-ray diffraction. Upon activation with either Et 2 AlCl or MAO, all the nickel complex pre-catalysts exhibited high activity toward ethylene polymerization over the temperature range from ambient to 50°C. In general, the bi-nuclear complexes showed a positive synergetic effect with higher activity than their mono nuclear analogs. The resultant polyethylene possessed higher molecular weight and a high degree of branching. † CCDC 917315, 917316 and 917317 for Ni1, Ni2-1 and Ni2-3. For ESI and crystallographic data in CIF or other electronic format see 1482 466410; Tel: +44 1482 465219 9176 | Dalton Trans., 2013, 42, 9176-9187 This journal is