The nuclear magnetic resonance spectra of a number of organosilieon compounds are examined. The 7.95 Mcs. silicon-29 spectra are obtained for these compounds and the chemical shifts are considered in detail. It is proposed that the trends observed are the result of a competition between two opposing effects; a paramagnetic shift influenced by changes in the effective nuclear charge on silicon and a diamagnetic shift influenced by (p→d)π bonding. The concept of the competitive shift mechanism rationalizes the chemical shifts observed for series of the type MexSiX₄₋x (where: X = 0Me,0Et, 0Ac, Cl, F and C₆H₅) but does not explain the shifts of silicon hydrides. This concept also rationalizes the trends observed in ¹¹⁹Sn chemical shifts but, logically, does not apply to ¹³C chemical shifts where the d-orbital contribution must vanish. None of the observed coupling constants correlate with the ²⁹Si chemical shifts. Available theories are found to be inadequate to describe the coupling constants in these molecules. A new long range coupling is observed between the methyl groups on silicon attached to oxygen and chlorine with J[subscript]HCSiCH of about 0.35 c.p.s. / Science, Faculty of / Chemistry, Department of / Graduate
| Identifer | oai:union.ndltd.org:UBC/oai:circle.library.ubc.ca:2429/36837 |
| Date | January 1966 |
| Creators | Hunter, Brian K. |
| Publisher | University of British Columbia |
| Source Sets | University of British Columbia |
| Language | English |
| Detected Language | English |
| Type | Text, Thesis/Dissertation |
| Rights | For non-commercial purposes only, such as research, private study and education. Additional conditions apply, see Terms of Use https://open.library.ubc.ca/terms_of_use. |
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