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dc.contributor.authorBreitling, Frank Michaelen
dc.date.accessioned2016-06-27T19:03:54Zen
dc.date.available2016-06-27T19:03:54Zen
dc.date.issued2005-08en
dc.identifiereprint:310en
dc.identifier.urihttp://hdl.handle.net/10919/71582en
dc.description.abstractGroup 3 and 4 complexes bearing linked cyclopentadienyl amido ligands, often referred to as constrained geometry complexes (CGCs), have experienced considerable interest due to their superior ability to copolymerise ethylene and higher alpha-olefins when activated with suitable co-catalyst.The work presented in this thesis aimed to replace the most commonly applied bridge in CGCs, which is silicon based, by one containing boron. The potential of the bridging element to have Lewis acidic character was expected to positively alter the catalytic activity of the activated species and possibly allowing for self-activation.Synthetic approaches to ligand precursors based on aminoboranes, diaminodiboranes(4) and ferrocenylboranes are described. Starting from the dihalo derivatives of these boranes, sequential substitution of the halides by one equivalent each of a cyclopentadienide derivative and an amide allowed the synthesis and isolation of a broad range of new CGC ligand precursors.Complexation of these ligand precursors to Group 4 metals was studied by utilising various protocols. The reaction with Group 4 tetraamides via amine elimination was the most successful yielding numerous new boron-bridged CGCs and related complexes in which the boron-bridged ligand binds in a non-chelating fashion.The newly synthesised compounds were fully characterised by multinuclear NMR spectroscopy, supplemented by X-ray diffraction studies where applicable.Studies on the reactivity of boron-bridged CGCs in the presence of alkylating agents indicated susceptibility of the boron atom to nucleophilic attack resulting in a decomposition of the linking moiety between the cyclopentadienyl and amido fragments. This is as well reflected in the data gathered from polymerisation experiments, in which methylaluminoxane activated boron-bridged CGCs displayed a low activity towards ethylene polymerisation, but a high activity towards styrene polymerisation. Such characteristics are comparable to unbridged compounds, e.g. [(eta5-C5H5)TiCl3], rather than silicon-bridged CGCs, thus suggesting degradation of the boron-bridged CGCs to unbridged complexes under polymerisation conditions.en
dc.format.mimetypeapplication/pdfen
dc.language.isoenen
dc.publisherUniversity of Londonen
dc.rightsIn Copyrighten
dc.rights.urihttp://rightsstatements.org/vocab/InC/1.0/en
dc.subjectboron titaniumen
dc.subjectzirconiumen
dc.subjecthafniumen
dc.subjectcomplex organometallicsen
dc.subjectcatalysisen
dc.subjectpolymerisationen
dc.subjectpolyolefinsen
dc.subjectpolyethyleneen
dc.subjectpolystyreneen
dc.subjectolefinsen
dc.subjectconstrained geometryen
dc.subjectconstraint geometryen
dc.subjectCGCen
dc.subject.lccQDen
dc.titleBoron-bridged constrained geometry complexes and related compoundsen
dc.typeDissertationen
dc.contributor.departmentPhilosophyen
thesis.degree.leveldoctoralen
thesis.degree.grantorImperial College Londonen


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