Synthesis and characterisation of permethylindenyl zirconium complexes and their use in ethylene polymerisation

We report the synthesis of two zirconocenes, dimethylsilylbis(hexamethylindenyl) zirconium dichloride, rac -(SBI*)ZrCl 2, and n butyldimethylsilyl(hexamethylindenyl) zirconium trichloride, [(Ind*SiMe 2 n Bu)Zr(μ-Cl)Cl 2 ] 2 . The complexes were characterised by NMR spectroscopy and X-ray crystallography, and the bonding was evaluated using density functional theory. rac -(SBI*)ZrCl 2 demonstrated a very high activity for solution phase polymerisation of ethylene ( ca. 22 500 kg PE −1 mol Zr −1 h −1 bar −1 ). Both rac -(SBI*)ZrCl 2 and rac -(EBI*)ZrCl 2 (EBI* = ethylenebis(hexamethylindenyl)) have been supported on MAO modified silica and AMOST layered double hydroxides (AMO-LDHs), and evaluated as catalysts in the slurry-phase polymerisation of ethylene. The highest catalytic polymerisation activities for rac -(SBI*)ZrCl 2 and rac -(EBI*)ZrCl 2 on the layered double hydroxides were 9657 and 4325 kg PE −1 mol Zr −1 h −1 bar −1 respectively, for MAO modified Mg 2 Al–SO 4 LDH. However, rac -(EBI*)ZrCl 2 was a three times more active catalyst than rac -(SBI*)ZrCl 2 when supported on silica.