Iron-catalysed dehydrocoupling/ dehydrogenation of amine- and phosphine-borane adducts
This Thesis describes the investigations of iron-catalysed dehydrocoupling/dehydrogenation of various amine- and phosphine-borane adducts. Chapter 1 gives a general introduction to mam group element-element bond forming reactions, focusing on transition metal-catalysed dehydrocoupling under mild con...
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| Format | Dissertation |
| Language | English |
| Published |
University of Bristol
2013
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| Online Access | Get more information |
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| Summary: | This Thesis describes the investigations of iron-catalysed dehydrocoupling/dehydrogenation of various amine- and phosphine-borane adducts. Chapter 1 gives a general introduction to mam group element-element bond forming reactions, focusing on transition metal-catalysed dehydrocoupling under mild conditions. Chapter 2 describes the use of a series of iron precatalysts in the dehydrocoupling of Me2NRBH3. Analysis by liB NMR spectroscopy allowed the identification of various intermediates to be made. Furthermore, it was found that in the case of dinuclear Fe(I) complexes that they reduced in situ to afford Fe(O) nanoparticles which were the active catalyst. Interestingly, a related mononuclear Fe(II) complex was found to generate a homogeneous catalyst which, while also dehydrocoupling Me2NRBH3 to produce [Me2N-BH2h as the final product, favoured the formation of a different intermediate than was detected in the case of the Fe nanoparticles. Chapter 3 describes the use of the same iron precatalysts in the dehydrocoupling of MeNH2·BH3 and H3N·BH3. It was found that they were all active towards these adducts which demonstrated the versatility of the Fe catalysts. FUlihermore, various polymeric and oligomeric products were formed depending on which precatalysts were employed. Chapter 4 describes the synthesis of a series of Fe-phosphidoborane complexes. These were then employed as dehydrocoupling catalysts for a variety of phosphine-borane adducts. Although they were shown to be poor catalysts for the dehydrocoupling of secondary phosphine-boranes, increased catalytic activity was observed in the analogous reactions with primary phosphine-boranes. Polyphosphinoboranes of high molecular weight were yielded as the sole products. Chapter 5 describes the on-going investigation and possible future work based on the research described in Chapters 2-4. |
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