TY - JOUR
T1 - Intramolecular electric field effect on a 1J(C,H) NMR spin-spin coupling constant. An experimental and theoretical study
AU - De Kowalewski, Dora G.
AU - Kowalewski, Valdemar J.
AU - Peralta, Juan E.
AU - Eskuche, Gernot
AU - Contreras, Rubén H.
AU - Esteban, Angel L.
AU - Galache, Maria P.
AU - Díez, Ernesto
PY - 1999/3
Y1 - 1999/3
N2 - 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.
AB - 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.
KW - 5-X-salicylaldehydes
KW - C NMR
KW - Intramolecular electric field
KW - J(C,H)
KW - NMR
UR - http://www.scopus.com/inward/record.url?scp=0033084271&partnerID=8YFLogxK
U2 - 10.1002/(sici)1097-458x(199903)37:3<227::aid-mrc438>3.0.co;2-2
DO - 10.1002/(sici)1097-458x(199903)37:3<227::aid-mrc438>3.0.co;2-2
M3 - Article
AN - SCOPUS:0033084271
SN - 0749-1581
VL - 37
SP - 227
EP - 231
JO - Magnetic Resonance in Chemistry
JF - Magnetic Resonance in Chemistry
IS - 3
ER -