A Highly Active Anilinotropone-Based Neutral Nickel(II) Catalyst for Ethylene Polymerization

The synthesis of a neutral nickel(II) complex
of 2-(2,6-diisopropylanilino)tropone is described. The
important attributes of this ligand include a hindered
N-aryl ring, a five-membered-ring chelate, and an
anionic N-donor. The complex has been characterized
in the solid state by X-ray crystallography, and relevant
features are discussed. The nickel complex is capable of
polymerizing ethylene with a turnover frequency of up
to 8.8 × 106 g of PE (mol of catalyst)-1 h-1 and of
producing polyethylenes with a wide range of branching
numbers by changes in pressure and temperature. The
catalyst shows an excellent tolerance for polar additives
in ethylene polymerization experiments and is quite
insensitive to added PPh3.