ORGANOMETALLIC NICKEL-CATALYSTS ANCHORED ON POLYMERIC MATRICES IN THE OLIGOMERIZATION AND/OR POLYMERIZATION OF OLEFINS .2. EFFECT AND ROLE OF THE COMPONENTS OF THE CATALYTIC-SYSTEM

Organometallic nickel complexes with bidentate (PO)-O-boolean AND chelating ligands of ylidic (-C(O)H=PPh(3)) and phosphino-acetic (-CH(PPh(3))-COOH) type heterogenized on polystyrene resins by anchoring through the carbon atom of the ligand have been prepared and used in the polymerization and/or oligomerization of ethylene. Their catalytic behaviour has been compared with those of corresponding homogeneous models and with heterogeneous species with the phosphine and oxygenated ligand bound in a non-chelated arrangement. The catalytic activity and selectivity are strongly dependent on the chelating strength of the ligand. The polymerization of ethylene to HDPE occurs with replica of the support morphology. The role of the ancillary ligand (phosphine, nitrogen bases, etc.) added to the systems has also been studied and clarified.