Through‐space 19 F– 19 F spin–spin coupling in ortho ‐fluoro Z ‐azobenzene
| Autor: | Cindy Salinas, Peter L. Rinaldi, Katherine Marie Martin, Christopher T. Brown, Christopher L. Dorsey, William J. Brittain, Shiva K. Rastogi, Jacob Armitage, Gao Chun, Justin Shi, Robert A. Rogers |
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| Rok vydání: | 2015 |
| Předmět: |
Coupling constant
010405 organic chemistry Chemical shift General Chemistry 010402 general chemistry Coupling (probability) Space (mathematics) 01 natural sciences E-Z notation 0104 chemical sciences chemistry.chemical_compound Crystallography Nuclear magnetic resonance Azobenzene chemistry General Materials Science Density functional theory Spin (physics) |
| Zdroj: | Magnetic Resonance in Chemistry. 54:126-131 |
| ISSN: | 1097-458X 0749-1581 |
| DOI: | 10.1002/mrc.4327 |
| Popis: | We report through-space (TS) (19)F-(19)F coupling for ortho-fluoro-substituted Z-azobenzenes. The magnitude of the TS-coupling constant ((TS) JFF ) ranged from 2.2-5.9 Hz. Using empirical formulas reported in the literature, these coupling constants correspond to non-bonded F-F distances (dFF) of 3.0-3.5 Å. These non-bonded distances are significantly smaller than those determined by X-ray crystallography or density functional theory, which argues that simple models of (19)F-(19)F TS spin-spin coupling solely based dFF are not applicable. (1)H, (13)C and (19)F 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 (19) F chemical shifts, and the calculated values deviated 0.3-10.0 ppm compared with experimental values. |
| Databáze: | OpenAIRE |
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