Abstract
Vicinal 1H, 13C coupling constants were measured for rigid unsaturated 1H-C-C=13C molecular frameworks at natural abundance. As a general trend, an empirical range of 4.5-6.5 Hz is observed independent of the value of the dihedral angle between the CH bond and the plane of the double bond. Furthermore, through-bond and through-space substituent effects also influence the magnitude of the coupling constants in a similar way to that known for saturated systems. In summary, two different additive transmission mechanisms take part in these coupling paths depending on the orientation of the π-system with respect to the allylic bond. The experimental evidence presented demonstrates the breakdown of the Karplus rule in this particular structural fragment.
| Original language | English |
|---|---|
| Pages (from-to) | 30-34 |
| Journal | Magnetic Resonance in Chemistry |
| Volume | 35 |
| Issue number | 1 |
| DOIs | |
| Publication status | Published - 1 Jan 1997 |
Keywords
- 1 H NMR
- Allylic systems
- Long-range proton-carbon coupling constants
- NMR
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Parella, T., Sánchez-Ferrando, F., & Virgili, A. (1997). Experimental evidence for the breakdown of the karplus relationship for 3J(13C, 1H) in 1H-C-C=13C systems. Magnetic Resonance in Chemistry, 35(1), 30-34. https://doi.org/10.1002/(SICI)1097-458X(199701)35:1<30::AID-OMR21>3.0.CO;2-0