New anilinotropone-based titanium complexes: synthesis, characterization and application as catalysts for olefin polymerization.

Abstract

New titanium(IV) dichloride complexes containing 2-anilinotropone ligands have been synthesized and characterized. Bis(ligand)titanium dichloride complexes 1 and 2 were synthesized from reaction of TiCl4(THF)2 with 2 equivalents of the corresponding sodium salts of 2-(2,6-diisopropylanilino)tropone (L1) and 2-(2,3,4,5,6-pentafluoroanilino)tropone (L2), respectively. The mixed cyclopentadienyl-anilinotropone compound 3 was synthesized by reaction of the lithium salt of with CpTiCl3. The Cp-mixed micro-O bimetallic complex 4 was also isolated as a by-product owing to the adventitious presence of moisture. The molecular structures 1-4 of have been determined by single-crystal X-ray diffraction studies. Complexes 1 and 2 are isostructural and exhibit a C2-symmetric octahedral geometry, with a trans(N,N), cis(O,O) arrangement in complex 1, but with a trans(O,O), cis(N,N) arrangement in complex 2. The Cp-mixed complex 3 has a distorted square-pyramidal structure with the Cp ligand in the apical position. Bimetallic complex 4 shows a similar coordination geometry for the five-coordinate titanium atom and a pseudo-tetrahedral coordination for the second metallic centre. All new complexes, when activated with methylaluminoxane, are active in the polymerization of ethylene and propene.