| Autor: |
Rastogi, Shiva K., Rogers, Robert A., Shi, Justin, Brown, Christopher T., Salinas, Cindy, Martin, Katherine M., Armitage, Jacob, Dorsey, Christopher, Chun, Gao, Rinaldi, Peter, Brittain, William J. |
| Předmět: |
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| Zdroj: |
Magnetic Resonance in Chemistry; Feb2016, Vol. 54 Issue 2, p126-131, 6p |
| Abstrakt: |
We report through-space (TS) 19F-19F coupling for ortho-fluoro-substituted Z-azobenzenes. The magnitude of the TS-coupling constant (TSJFF) ranged from 2.2-5.9Hz. Using empirical formulas reported in the literature, these coupling constants correspond to non-bonded F-F distances (dFF) of 3.0-3.5Å. These non-bonded distances are significantly smaller than those determined by X-ray crystallography or density functional theory, which argues that simple models of 19F-19F TS spin-spin coupling solely based dFF are not applicable. 1H, 13C and 19F data are reported for both the E and Z isomers of ten fluorinated azobenzenes. Density functional theory [B3YLP/6-311++G(d,p)] was used to calculate 19F chemical shifts, and the calculated values deviated 0.3-10.0ppm compared with experimental values. [ABSTRACT FROM AUTHOR] |
| Databáze: |
Complementary Index |
| Externí odkaz: |
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