Striking different behavior in the activation of alfa-olefins by homogeneous and heterogenized catalysts based on mu5-cyclopentadienyl nickel derivatives

Homogeneous eta 5-cyclopentadienyl nickel catalysts have been applied to ethylene oligomerization. Their activity, enhanced by the presence of Al(OEt)Et(2) as co-catalyst, resulted the highest up to now reported for this type of complexes. The same catalytic systems were also able to oligomerize propylene as well as ethylene/propylene mixtures, in particular propylene was converted into branched dimers, mostly 2,3-dimethylbutenes. Heterogenization of the above system, carried out by anchoring the nickel derivative to a styrene/divinylbenzene resin properly functionalized with the cyclopentadienyl group, caused a drastic change of the selectivity of the process, ethylene polymerization to HDPE taking place instead of oligomerization.