Biphasic Ni-Catalyzed Ethylene Oligomerization in Ionic Liquids

Diimine nickel complexes activated with aluminoxane in chloroaluminate ionic liquids are highly active catalysts either for the biphasic ethylene oligomerization or for polymerization depending on the bulkiness of the diimine ligand. The activation of Ni(0) with a Bronsted acid in different non-chloroaluminate ionic liquids is also reported. The nature of the ionic liquid and the presence or not of a nitrogen ligand affect significantly the catalytic performances. The olefinic products are weakly soluble in ionic liquids and can be separated from the catalytic ionic phase by simple decantation. The nickel catalysts are immobilized and stabilized in the ionic liquids and can be recycled.