Substituted indenyl complexes for ethylene polymerisation

Abstract

The principle aims of this thesis have been to synthesise novel substituted indenyl complexes inspired by the very active Me2SBI*ZrCl2. By looking to improve on the ethylene polymerisation activity and the racemo-selectivity, the Me2SBI* ligand framework has been modified. The synthesised complexes have been tested for homogeneous and heterogeneous ethylene polymerisation activity and evaluated for their potential industrial applications. Chapter One provides a background to the chemistry of cyclopentadienyl and indenyl ligands, group 4 ansa-metallocenes and their ethylene polymerisation activity. The mechanism of ethylene polymerisation is reviewed. A summary of the development of homogeneous and heterogeneous ethylene polymerisation is discussed including the use of solid supports; silica, solid polymethylaluminoxane (sMAO) and layered double hydroxides. Chapter Two describes modification of the Me2SBI* ligand by introducing different alkyl and aryl groups on the silyl bridge and at the 3position of the indenyl rings. Et2SBI*H2, nPr,MeSBI*H2, All,MeSBI*H2 and Me2SB(3EtI*)H2 pro-ligands have been synthesised. All pro-ligands and their synthetic intermediates have been fully characterised by NMR spectroscopy. Chapter Three details the synthesis of substituted indenyl group 4 complexes. All complexes have been fully characterised by single crystal X-ray diffraction and NMR spectroscopy. Comparisons of the crystal structure metrical parameters are made. Chapter Four investigates the homogeneous and heterogeneous ethylene polymerisation activity of the synthesised substituted indenyl complexes. The complexes have been immobilised onto sMAO and characterised by solid state NMR spectroscopy and SEM. The resulting polyethylenes have been characterised by GPC, XRD and SEM. Chapter Five studies the solid support comparison between sMAO, SSMAO and LDHMAO. The optimisation of polymerisation conditions for the sMAO-[Me2SB(3-EtI*)ZrCl2] catalyst has been carried out. Potential industrial applications including polyethylene waxes and LLDPE have been explored. Chapter Six provides experimental details and characterising data for the preceding chapters. Electronic appendix contains the CIF, CheckCIF and PLATON files of all single crystal structures.</p