Zr(IV), Ti(IV), and V(III) complexes of some benzimidazole, benzothiazole, andbenzoxazole ligands: characterization and catalyst efficiency in ethylenepolymerization

Abstract

Fifteen complexes of 2, 2-bis- (benzimidazole, benzothiazole, and benzoxazole) compounds with Zr(IV),Ti(IV), and V(III) metal centers were synthesized, characterized, activated with methyalumoxane (MAO), and thentested for catalytic ethylene polymerization. The activities of the various catalysts were found to be functions of thehetero atoms in the ligand frameworks. The activity of the catalyst system6/MAO was found to be 1372 kg PE/mol cat.h. The polyethylene produced with the catalyst system6/MAO showed high molecular weights (1.84 106g/mol) andbroad molecular weight distributions (PD = 11). This could result from different interactions of the MAO counter ionwith the heteroatoms of the catalyst ligand generating different active sites. The effect of the polymerization temperatureof the polymers produced with catalyst6/MAO was also investigated.