STRIKING DIFFERENT BEHAVIOR IN THE ACTIVATION OF ALPHA-OLEFINS BY HOMOGENEOUS AND HETEROGENIZED CATALYSTS BASED ON ETA-5-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 reporte d for this type of complexes. The same catalytic systems were also abl e to oligomerize propylene as well as ethylene/propylene mixtures, in particular propylene was converted into branched dimers, mostly 2,3-di methylbutenes. Heterogenization of the above system, carried out by an choring the nickel derivative to a styrene/divinylbenzene resin proper ly functionalized with the cyclopentadienyl group, caused a drastic ch ange of the selectivity of the process, ethylene polymerization to HDP E taking place instead of oligomerization.