The dehydrogenative coupling reactions of phenylsilane (PhSiH$ sb3$) with the following bridged and unbridged bis(indenyl) complexes: ($ eta sp5$-C$ sb9$H$ sb7) sb2$MMe$ sb2$ (1), ($ rm eta sp5$-$ rm C sb9H sb{11}) sb2MMe sb2$ (2), $ rm (CH sb2) sb2( eta sp5$-$ rm C sb9H sb6) sb2MMe sb2$ (3) and $ rm (CH sb2) sb2( eta sp5$-$ rm C sb9H sb{10}) sb2MMe sb2$ (4) (where M = Ti (a) and Zr (b); and Me = CH$ sb3$), were investigated. Some of these reactions were monitored by $ sp1$H- and $ sp{29}$Si-NMR, and by gel permeation chromatography (GPC). The oligosilanes obtained generally showed a polymodal molecular weight distribution. During the reaction of PhSiH$ sb3$ with 1a, a new dititanium complex was isolated: $( mu$-$ rm eta sp6{:} eta sp5$-$ rm C sb9H sb7)( mu$-$ rm H) sb2 lbrack ( eta sp5$-$ rm C sb9H sb7)Ti rbrack sb2$. The structure of this compound was confirmed by X-ray diffraction analysis, by infrared spectroscopy, and by electron paramagnetic resonance (EPR). Some possible mechanisms for the formation of this complex, along with the origin of its short Ti-Ti distance (2.745 A), were discussed. For the other systems, it was shown that the catalytic activity was strongly dependent on the nature of the metal, and on the structure of the ligands surrounding it. The titanium-based catalysts seemed to be more efficient to produce linear oligosilanes having degrees of polymerization (DP) of 12 or 18, depending on the systems. Cyclic oligomers, having DP's of 6-7, were more specifically obtained with the zirconium-based catalysts. The only system having shown a certain kind of stereocontrol was the one based on 3b.
| Identifer | oai:union.ndltd.org:LACETR/oai:collectionscanada.gc.ca:QMM.70249 |
| Date | January 1992 |
| Creators | Gauvin, François |
| Publisher | McGill University |
| Source Sets | Library and Archives Canada ETDs Repository / Centre d'archives des thèses électroniques de Bibliothèque et Archives Canada |
| Language | English |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Format | application/pdf |
| Coverage | Doctor of Philosophy (Department of Chemistry.) |
| Rights | All items in eScholarship@McGill are protected by copyright with all rights reserved unless otherwise indicated. |
| Relation | alephsysno: 001287871, proquestno: AAINN74459, Theses scanned by UMI/ProQuest. |
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