Group 4 permethylindenyl constrained geometry complexes for ethylene polymerisation catalysis

Abstract

We report the synthesis and characterisation of six permethylindenyl constrained geometry complexes of the type ^Me₂SB(^RN,I*)TiCl₂ ({(η⁵-C₉Me₆)Me₂Si(^RN)}TiCl₂; R = i-Pr, t-Bu, n-Bu, Ph, 4-t-BuPh and 4-n-BuPh). Three complexes (R = i-Pr, t-Bu and 4-t-BuPh) have been structurally characterised using single crystal X-ray diffraction. Reaction with solid polymethylaluminoxane (sMAO) yields solid catalysts active for the slurry phase polymerisation of ethylene. The activities increase with increasing electron donating character of the amido fragment. ^Me₂SB(^t-BuN,I*)TiCl₂ exhibits an activity of 3602 kg_PE mol_Ti⁻¹ h⁻¹ bar⁻¹ (30 minutes, 2 bar ethylene), an activity significantly greater than the previously synthesised ^Me₂SB(^t-BuN,Cp*)TiCl₂.