This thesis describes the synthesis and characterisation of new mononuclear and binuclear zirconium and hafnium compounds containing ansa-bridged ligands. Some olefin polymerization studies, employing the new compounds as catalysts, are also presented. <strong>Chapter 1</strong> begins with an introduction to Ziegler-Natta polymerization of olefins, concentrating on recently developed metallocene-based catalyst systems. The second part of the Chapter charts the development of group 4 ansa-metallocene derivatives, especially their use as stereospecific catalysts. Finally, a review of binuciear group 4 metallocene compounds containing bridging bis(cyclopentadienyl)-type ligands is presented. <strong>Chapter 2</strong> describes the synthesis and characterisation of some novel mononuclear metallocene compounds of zirconium and hafnium containing ansa-bridged ligands. The ansa-bridged mononuclear compounds [{Me<sub>2</sub>C(η<sup>5</sup>-C<sub>5</sub>H<sub>4</sub>)(η<sup>2</sup>-C<sub>9</sub>H<sub>6</sub>)}M(η<sup>5</sup>C<sub>5</sub>H<sub>5</sub>)Cl] (M = Zr, Hf), [{(CH<sub>2</sub>)<sub>5</sub>C(η<sup>5</sup>-C<sub>5</sub>H<sub>4</sub>)(η<sup>2</sup>-C<sub>9</sub>H<sub>6</sub>)}M(η<sup>5</sup>-C<sub>5</sub>H<sub>5</sub>)Cl] (M = Zr, Hf) and [{Me<sub>2</sub>(η<sup>5</sup>-C<sub>5</sub>H<sub>4</sub>)(η<sup>3</sup>-C<sub>13</sub>H<sub>8</sub>)}Zr(η<sup>5</sup>-C<sub>5</sub>H<sub>5</sub>)Cl] are described, along with the X-ray crystal structures of the zirconium compounds. The η<sup>2</sup>-indenyl and η<sup>3</sup>-fluorenyl coordination modes observed for these compounds are unprecedented. The synthesis and characterisation of the novel, mononuclear ansa-bridged compounds [{Me<sub>2</sub>C(η<sup>5</sup>-C<sub>5</sub>H<sub>4</sub>)<sub<2</sub>}M(η<sup>5</sup>-C<sub>5</sub>H<sub>5</sub>)Cl] (M = Zr, Hf) is also described, along with their X-ray crystal structures. The variable temperature solid state <sup>13</sup>C CP/MAS NMR spectra of [{Me<sub>2</sub>C(η<sup>5</sup>-C<sub>5</sub>H<sub>4</sub>)<sub<2</sub>}M(η<sup>5</sup>-C<sub>5</sub>H<sub>5</sub>)Cl] (M = Zr, Hf) show slow rotation of the C<sub>5</sub>H<sub>5</sub> ring on the NMR timescale. <strong>Chapter 3</strong> describes the synthesis and characterisation of some novel homo- and hetero-binuclear metallocene compounds of zirconium and hafnium in which the metals are bridged by an unsymmetrical ansa ligand. The novel, chiral homobinuclear compounds [(η<sup>5</sup>-C<sub>5</sub>H<sub>5</sub>)MCl<sub>2</sub>{(η<sup>5</sup>-C<sub>5</sub>H<sub>4</sub>)CMe<sub>2</sub>(η<sup>5</sup>-C<sub>9</sub>H<sub>6</sub>)}MCl<sub>2</sub>(η<sup>5</sup>-C<sub>5</sub>H<sub>5</sub>)] (M = Zr, Hf) are described. The ansa-bridged mononuclear compounds [{Me<sub>2</sub>C(η<sup>5</sup>-C<sub>5</sub>H<sub>4</sub>)(η<sup>2</sup>-C<sub>9</sub>H<sub>7</sub>)M(η<sup>5</sup>-C<sub>5</sub>H<sub>5</sub>)Cl] (M = Zr, Hf) are used as reagents for the selective synthesis of the heterobinuclear analogues [(η<sup>5</sup>-C<sub>5</sub>H<sub>5</sub>)MCl<sub>2</sub>{(η<sup>5</sup>-C<sub>5</sub>H<sub>4</sub>)CMe<sub>2</sub>(η<sup>5</sup>-C<sub>9</sub>H<sub>6</sub>)}M*Cl<sub>2</sub>(η<sup>5</sup>-C<sub>5</sub>H<sub>5</sub>)] (M = Zr, M* = Hf ; M = Hf, M* = Zr) and the unsymmetrical homobinuclear compound [(η<sup>5</sup>-C<sub>5</sub>H<sub>5</sub>)ZrCl<sub>2</sub>{(η<sup>5</sup>-C<sub>5</sub>H<sub>4</sub>)CMe<sub>2</sub>(��<sup>5</sup>-C<sub>9</sub>H<sub>6</sub>)}ZrCl<sub>2</sub>(η<sup>5</sup>-C<sub>5</sub>Me<sub>5</sub>)]. The methylated derivatives [(η<sup>5</sup>-C<sub>5</sub>H<sub>5</sub>)M(CH<sub>3</sub>)<sub>2</sub>{(η<sup>5</sup>-C<sub>5</sub>H<sub>4</sub>)CMe<sub>2</sub>(η<sup>5</sup>-C<sub>5</sub>H<sub>6</sub>)}M*(CH<sub>3</sub>)<sub>2</sub>(η<sup>5</sup>-C<sub>5</sub>H<sub>5</sub>)] (M = Zr, M* = Zr, Hf; M = Hf, M* = Zr, Hf) are also described. The structurally related mononuclear compounds [(η<sup>5</sup>-C<sub>5</sub>H<sub>5</sub>)MCl<sub>2</sub>{(η<sup>5</sup>-C<sub>5</sub>H<sub>4</sub>)CMe<sub>2</sub>(C<sub>9</sub>H<sub>7</sub>)}] (M = Zr, Hf) and [(η<sup>5</sup>-C<sub>5</sub>H<sub>5</sub>)Zr(CH<sub>3</sub>)<sub>2</sub>{(η<sup>5</sup>-C<sub>5</sub>H<sub>4</sub>)CMe<sub>2</sub>(C<sub>9</sub>H<sub>7</sub>)}] have also been prepared. <strong>Chapter 4</strong> presents some olefin polymerization studies using the new compounds described in Chapter 3 as catalysts, along with either methylaluminoxane or the recently developed co-catalysts [Ph<sub>3</sub>C]<sup>+</sup>[B(C<sub>6</sub>F<sub>5</sub>)<sub>4</sub>]<sup>-</sup> and B(C<sub>6</sub>F<sub>5</sub>)<sub>3</sub>. <strong>Chapter 5</strong> provides the experimental details for the reactions described in this thesis and the characterising data for all new compounds are given in <strong>Chapter 6</strong> Crystallographic data for the for the X-ray structure determinations in Chapter 2 are given in the <strong>Appendices</strong>.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:359411 |
| Date | January 1994 |
| Creators | Diamond, Gary M. |
| Contributors | Green, M. L. H. |
| Publisher | University of Oxford |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | http://ora.ox.ac.uk/objects/uuid:297bc125-5270-4969-89c3-69fd326e5c02 |
Page generated in 0.0021 seconds