Very active neutral P,O-Chelated nickel catalysts for ethylene polymerization

A series of highly active nickel-based neutral catalysts for ethylene polym erization is presented. These catalysts are obtained by direct complexation of simple fluorinated ketoylides onto bis-(1,5-cyclooctadiene)nickel. Cata lyst formation readily occurs in the presence of an olefin, but due to the electron deficiency of the ligand, it hardly happens in the absence of an o lefin or another Lewis base. Activities greater than 2 x 10(6) (g(PE)/g(Ni) )/h and productivities higher than 15 x 10(6) g(PE)/mol(Ni) are typically o bserved. These catalysts are also active for the polymerization of a-olefin s such as l-hexene and l-propene. Polymer characterization indicates that h ighly linear, low molecular weight PEHD is formed by these complexes.