On-Purpose Oligomerization by 2-t-Butyl-4-arylimino-2,3-dihydroacridylnickel(II) Bromides

In this study, 2-t-butyl-4-arylimino-2,3-dihydroacridylnickel dibromides were synthesized by nickel-template one-pot condensation, and well characterized along with the single-crystal X-ray diffraction to one representative complex, revealing a distorted tetrahedral geometry around nickel. When activated with modified methylaluminoxane (MMAO), all nickel complexes exhibited high activities (up to 1.91 × 10⁶ g mol⁻¹ (Ni) h⁻¹) toward major trimerization of ethylene. When activated with ethylaluminum dichloride (EtAlCl₂), however, the title complexes performed good activities (up to 1.05 × 10⁶ g mol⁻¹ (Ni) h⁻¹) for selective dimerization of ethylene. In comparison to analogous nickel complexes, higher activities were achieved with the substituent of t-butyl group, especially in the rare case of nickel complexes performing trimerization of ethylene.