Medium effects on the fluorine chemical shifts of non-polar molecules in liquids |
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Authors: | WT Raynes MA Raza |
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Institution: | Department of Chemistry , University of Sheffield , S3 7HF |
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Abstract: | The gas-to-infinite dilution fluorine chemical shifts of CF4, SiF4, SF6, C6F6, p-fluorotoluene and p-difluorobenzene have been measured for a series of non-polar solvents. Downfield displacements ranging from 3–16 p.p.m. have been observed. Comparisons with proton solvent shifts make it evident that the London dispersion forces are the principal agent in causing the shifts. However, unlike proton resonance where the local diamagnetic shielding is mostly affected, it is probably through the local paramagnetic shielding that solvents alter fluorine chemical shifts. |
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