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


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 then tested for catalytic ethylene polymerization. The activities of the various catalysts were found to be functions of the hetero atoms in the ligand frameworks. The activity of the catalyst system \textbf{6}/MAO was found to be 1372 kg PE/mol cat. h. The polyethylene produced with the catalyst system 6/MAO showed high molecular weights (1.84 $\times $ 10$^{6}$ g/mol) and broad molecular weight distributions (PD = 11). This could result from different interactions of the MAO counter ion with the heteroatoms of the catalyst ligand generating different active sites. The effect of the polymerization temperature of the polymers produced with catalyst 6/MAO was also investigated.

Keywords: Bis-benzimidazole, bis-benzoxazole, bis-benzothiazole, complexes, homogeneous ethylene polymerization

Full Text: PDF