Synthesis of zirconocene complexes and their use in slurry-phase polymerisation of ethylene

Abstract

A new family of zirconocene complexes of the type (3-RInd#)2ZrX2(where Ind#= C6Me5H and R = Me, Et and Ph) have been synthesised and fully characterised. Six new crystal structures have been reported (meso-(3-EtInd#)2ZrBr2,rac-(3-EtInd#)2ZrCl2,rac-(3-EtInd#)2Zr(CH2Ph)2,meso-(3-EtInd#)2Zr(CH2Ph)2,meso-(3-MeInd#)2ZrBr2andmeso-(3-MeInd#)2Zr(CH2Ph)2). The complexes were studied for slurry-phase ethylene polymerisation when immobilised on solid polymethylaluminoxane (sMAO). Variation in the initiation group was found to have greater influence over polymerisation activity formeso-catalysts thanrac-catalysts, withmeso-alkyl catalysts showing higher polymerisation activities thanmeso-halide. Below 70 °C, polymerisation activity follows the order sMAO-meso-(3-EtInd#)2Zr(CH2Ph)2,sMAO-meso-(3-EtInd#)2ZrCl2and sMAO-meso-(3-EtInd#)2ZrBr2(activities of 657, 561, and 452 kgPEmolM−1h−1bar−1, respectively). sMAO-meso-(3-EtInd#)2ZrBr2produces HDPE with the highest molecular weight, followed by sMAO-meso-(3-EtInd#)2ZrCl2and sMAO-meso-(3-EtInd#)2Zr(CH2Ph)2(Mwof 503, 406, and 345 kg mol−1, respectively, at 50 °C). sMAO-meso-(3-MeInd#)2ZrBr2produced HDPE with almost identical molecular weights to sMAO-meso-(3-EtInd#)2ZrCl2(395 kg mol−1at 50 °C).