This thesis describes the synthesis and characterisation of a series of cationic rhodium bis-phosphine complexes. The reactivity of these new complexes in the solid-state and in solution is reported. In <b>Chapter 2</b> the synthesis of a series of rhodium bis-phosphine diene complexes is presented and the reactions of these complexes with hydrogen in the solid-state are investigated. Several examples of zwitterionic complexes coordinating the [BAr<sup>F</sup>4]<sup>─</sup> anion are produced by hydrogenation. A rare example of a sigma-alkane complex, [Rh(<sup>i</sup>Bu<sub>2</sub>PCH<sub>2</sub>CH<sub>2</sub>P<sup>i</sup>Bu<sub>2</sub>)(eta<sup>2</sup>-<sub>CH</sub>-eta<sup>2</sup>-<sub>CH</sub>-NBA][BAr<sup>F</sup>4]<sup>─</sup], is also formed in the solid-state, by a single crystal to single crystal transition driven by hydrogen. This complex is crystallographically characterised and displays two short Rh∙∙∙H−C sigma-interactions. Deuteration studies indicate that the agostic complex [Rh(<sup>i</sup>Bu<sub>2</sub>PCH<sub>2</sub>CH<sub>2</sub>P<sup>i</sup>Bu<sub>2</sub>)(eta<sup>2</sup>-<sub>CH</sub>-eta<sup>2</sup>-<sub>CH</sub>-NBE][BAr<sup>F</sup>4] may form as a short lived intermediate prior to the formation of the sigma-alkane complex. The temporal evolution of the solid-state hydrogenation reactions is monitored by powder X-ray diffraction methods. In <b>Chapter 3</b> the C−X activation of various aryl halides using the [Rh(<sup>i</sup>Bu<sub>2</sub>PCH<sub>2</sub>CH<sub>2</sub>P<sup>i</sup>Bu<sub>2</sub>)]<sup>+</sup> fragment is reported. The 'ligand innocence' of the phosphine with respect to intramolecular C−H activation is also discussed. A rare example of C−X activation in the solid-state is presented, which shows the formation of an isomer that is not observed by analogous solution routes. <b>Chapter 4</b> investigates solid-state ligand exchange reactions using ethene, butadiene, CO and NH3 gases. A solid-state transfer dehydrogenation reaction is reported within single crystals of [Rh(<sup>i</sup>Bu<sub>2</sub>PCH<sub>2</sub>CH<sub>2</sub>P<sup>i</sup>Bu<sub>2</sub>)(C<sub>2</sub>H<sub>4</sub>)<sub>2</sub>][BAr<sup>F</sup>4]. H/D exchange of NH3 can also occur in the solid state in the bis-ammonia complex [Rh(<sup>i</sup>Bu<sub>2</sub>PCH<sub>2</sub>CH<sub>2</sub>P<sup>i</sup>Bu<sub>2</sub>)(NH<sub>3</sub>)<sub>2</sub>][BAr<sup>F</sup>4]. A variety of rhodium complexes are tested as heterogeneous catalysts for the hydrogenation of ethene and the isomerisation of butene. In <b>Chapter 5</b> the binding affinity of a variety of fluorinated arenes to rhodium bis-phosphine fragments is presented using ESI-MS methods. The dependence upon the arene substituents, phosphine substituents and phosphine bite angle are discussed.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:635278 |
| Date | January 2014 |
| Creators | Pike, Sebastian David |
| Contributors | Weller, Andrew S. |
| Publisher | University of Oxford |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | http://ora.ox.ac.uk/objects/uuid:413c8a57-0a5e-4e51-8874-e48db8079675 |
Page generated in 0.0032 seconds