Nitrogen-15 magnetic resonance spectroscopy of compounds containing the nitrogen-nitrogen bond.
Item
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Title
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Nitrogen-15 magnetic resonance spectroscopy of compounds containing the nitrogen-nitrogen bond.
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Identifier
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AAI9029943
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identifier
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9029943
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Creator
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Huang, Xiaohua.
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Contributor
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Adviser: Theodore Axenrod
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Date
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1990
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Language
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English
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Publisher
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City University of New York.
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Subject
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Chemistry, Organic
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Abstract
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This dissertation is divided into four parts. The first part deals with a brief description of the nitrogen-15 NMR spectroscopy with a special emphasis on the theory and applications of chemical shifts and coupling constants in the investigation of structures of organic compounds. The second part covers the application of carbon-13 and nitrogen-15 NMR spectroscopy to the study of benzenediazonium ions, namely, the influence of aromatic ring-substituents, solvents and specific complexing agents such as crown ethers, on the structure and bonding in benzenediazonium ions. The use of one-bond carbon-nitrogen spin-spin coupling constants as a probe of the electronic structure and of the C{dollar}\sb1{dollar}-N{dollar}\alpha{dollar} bond order in the benzenediazonium ions with specific examples is included. Electron-donating groups on the benzenediazonium ions induce larger changes in the one-bond C{dollar}\sb1{dollar}-N{dollar}\alpha{dollar} and N{dollar}\alpha{dollar}-N{dollar}\beta{dollar} coupling constants whereas electron-withdrawing groups produce only small changes in the coupling. Further, both the electron-donating and electron-withdrawing groups do effect the bond order of the C{dollar}\sb1{dollar}-N{dollar}\alpha{dollar}. Also, bulky substituents in the 3,5-positions in the ring affect differently the coupling constants. It is concluded that solvents with large donor numbers (DN) enhance the diazonium type structures in the benzenediazonium ions. Complexation of benzenediazonium ions with crown ethers causes an increase in the single bond character of the C{dollar}\sb1{dollar}-N{dollar}\alpha{dollar}. Further, the crown ethers with different cavity sizes seem to stabilize the benzenediazonium ions by different modes of interaction and the bulky ortho substituents do tend to destabilize the crown ether complex. The third part includes an investigation of hydrazine and its derivatives. It is demonstrated that the nitrogen-nitrogen one-bond coupling constants have an explicit dependence on the conformation of the adjacent lone-pair electrons. The last part of this thesis details the experimental procedures adopted in the synthesis of the various benzenediazonium ions and their precursors.
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Type
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dissertation
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Source
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PQT Legacy CUNY.xlsx
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degree
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Ph.D.
