Titanium and Zirconium Catalysts with [N,O] Ligands: Syntheses, Characterization, and Their Catalytic Properties for Olefin Polymerization

Abstract

A series of titanium and zirconium complexes L2MCl2 bearing salicylbenzoxazole ligands 2-(5-R-benzoxazol-2-yl)-6-R1-4-R2-phenol (L) (2a, M = Ti, R1 = R2 = tBu, R = H; 2j, M = Ti, R1 = cumyl, R2 = tBu, R = H; 2k, M = Ti, R1 = Ad, R2 = tBu, R = H; 3a, M = Zr, R1 = R2 = tBu, R = H; 3b, M = Zr, R1 = R2 = tBu, R = CH3; 3c, M = Zr, R1 = R2 = tBu, R = tBu; 3d, M = Zr, R1 = R2 = tBu, R = Cl; 3e, M = Zr, R1 = R2 = tBu, R = NO2; 3f, M = Zr, R1 = H, R2 = H, R = H; 3g, M = Zr, R1 = CH3, R2 = H, R = H; 3h, M = Zr, R1 = tBu, R2 = H, R = H; 3i, M = Zr, R1 = tBu, R2 = CH3, R = H; 3j, M = Zr, R1 = cumyl, R2 = tBu, R = H; 3k, M = Zr, R1 = Ad, R2 = tBu, R = H) were synthesized. All the ligands and the metal complexes were fully characterized by 1H and 13C NMR spectra and elemental analyses. The molecular structures of 3b,d,i,j were determined by single-crystal X-ray diffraction methods. Upon activation with methylaluminoxane (MAO), the zirconium complexes 3a–e,h–k bearing a bulky substitute on the ortho position of the phen...