This thesis is concerned with the application of the SARACEN method to a range of molecules with interesting structural properties and applications in industry. The gas-phase structures of a series of compounds have been obtained, combining gas-phase electron diffraction and <i>ab initio </i>molecular orbital theory. For each compound a series of the potential energy surface was carried out to investigate the number of conformational minima and to locate the global energy minimum. The gas-phase structures of <i>trans-</i>1,2-dichloro-1,2-disilylethene (1), 1,1-bromosilylethene (2) and 1,1,1,4,4,4-hexachloro-1,4-disilabutane (3) were studied and <i>ab initio </i>calculations on analogous compounds were carried out. This study revealed extreme asymmetry in coordination at carbon, and trends in bond lengths and angles were interpreted in terms of cumulative electronic and steric contributions. The structure of bistrichlorosilyldimethylgermane [(Me<sub>2</sub>Ge(SiCl<sub>3</sub>)<sub>2</sub>] (4) was determined <i>ab initio </i>and by gas-phase electron diffraction and compared to that of a previously determined trimethyl analogue. An important difference between experimental and theoretical results was revealed. Three silylhydrazines, F<sub>3</sub>SiN(Me)NMe<sub>2</sub> (5) and F<sub>3</sub>SiN(SiMe<sub>3</sub>)NMe<sub>2</sub> (6) ClH<sub>2</sub>SiN(Me)NMe<sub>2</sub> (7), have been studied <i>ab initio </i>and by gas-phase electron diffraction. Previous solid- and gas-phase investigations of other substituted silylhydrazines revealed unusually narrow Si-N-N bond angles. Structural investigations were initiated for the halogen and bulky alkyl-substituted compounds to gauge the effects of these different substitutions on the Si-N-N bonds angles. Further calculations were carried out on similar compounds upon removing the “donor” and “acceptor” atoms, to verify the presence of suspected Si β-N interactions.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:666324 |
| Date | January 2004 |
| Creators | McLachlan, Lorna J. |
| Publisher | University of Edinburgh |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | http://hdl.handle.net/1842/15345 |
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