Intramolecular electric field effect on a 1J(C,H) NMR spin-spin coupling constant. An experimental and theoretical study
An experimental study of the effects of intramolecular electric fields on 1J(C,H) coupling constants involving a formyl proton in a series of 5-X-salicylaldehydes is reported. The particularly large electric field component along the Cc-Hf bond, calculated for X = NO2, leads to a measured substituen...
Guardado en:
| Autores principales: | , , , , , , , |
|---|---|
| Formato: | JOUR |
| Materias: | |
| Acceso en línea: | http://hdl.handle.net/20.500.12110/paper_07491581_v37_n3_p227_DeKowalewski |
| Aporte de: |
| Sumario: | An experimental study of the effects of intramolecular electric fields on 1J(C,H) coupling constants involving a formyl proton in a series of 5-X-salicylaldehydes is reported. The particularly large electric field component along the Cc-Hf bond, calculated for X = NO2, leads to a measured substituent effect of 7.36 Hz. For other X substituents a linear correlation was found between the calculated substituent electric field component along the Cc-Hf bond and the substituent effect on 1J(Cc,Hf). To determine if 5-X substituents affect the intramolecular C=O⋯H-O hydrogen bond, NBO analyses were carried out on 5-NO2- and 5-H-salicylaldehyde, and they were compared with those corresponding to benzaldehyde and phenol. The effects of interactions other than the electrostatic one on 1J(Cc,Hf) couplings were ruled out. The experimental results are in agreement with theoretical predictions published previously. Copyright © 1999 John Wiley & Sons, Ltd. |
|---|