Effect of aryloxo substituents in ethylenepolymerisation by tris(pyrazolyl)borate titanium(IV) complexes containing aryloxo ligands of type, TpTiCl2(OAr)

Abstract

Tris(pyrazolyl)borate titanium(IV) complexes containing aryloxo ligand of type, TpTiCl₂(OAr) [Tp = HB(pyrazolyl)₃; Ar = 2-ⁱPrC₆H₄, C₆F₅, 2,6-Ph₂C₆H₃], have been prepared, identified, and the structures of TpTiCl₂(OC₆F₅), TpTiCl₂(O-2,6-Ph₂C₆H₃) have been determined by X-ray crystallography. The 2-ⁱPrC₆H₄ analogue exhibits especially high catalytic activities for ethylene polymerisation in the presence of methylaluminoxane (MAO), and the activity by TpTiCl₂(OAr) increased in the order: Ar = 2-ⁱPrC₆H₄ > Ph > C₆F₅ >> 2,6-Ph₂C₆H₃ > 2,6-Me₂C₆H₃, 2,6-ⁱPr₂C₆H₃.