Natural J coupling (NJC) analysis of the electron lone pair effect on NMR couplings:: Part 1.: The lone pair orientation effect of an α-nitrogen atom on 1J(C,C) couplings

被引:49
作者
Barone, V
Peralta, JE
Contreras, RH
Sosnin, AV
Krivdin, LB
机构
[1] Univ Buenos Aires, Fac Ciencias Exactas & Nat, Dept Fis, RA-1428 Buenos Aires, DF, Argentina
[2] Tech Acad Angarsk, Dept Chem, Angarsk 665835, Russia
关键词
NMR; natural J couplings; indirect spin-spin couplings; lone-pair effect; bond contributions; NBO interactions;
D O I
10.1002/mrc.901
中图分类号
O6 [化学];
学科分类号
0703 ;
摘要
The known lone pair orientation effect of an a-nitrogen atom on (1)J(C,C) couplings was studied using the natural J coupling (NJC) dissection method for the Fermi contact (FC) term. This dissection was performed at the DFT-B3LYP level using three different basis sets. It was verified that non-contact contributions, which are much smaller than the FC term, do not depend on the orientation of the N lone pair. Acetone oxime (1), protonated acetone oxime (2) and ethylamine (3), were taken as model compounds to perform this study. In 1 the difference between (1)J(Z) and (1)J(E) is mainly determined by three NJC terms, i.e the nitrogen lone pair, the carbon-carbon bond containing the coupled carbon atoms and the carbon inner core orbitals contributions. In 3 the angular dependence of (1)J(C,C) vs the amine group conformation is dominated by the same three contributions that define the (1)J(Z) and (1)J(E) difference in 1. Copyright (C) 2001 John Wiley & Sons, Ltd.
引用
收藏
页码:600 / 606
页数:7
相关论文
共 48 条
[1]   LONG-RANGE PROTON SPIN-SPIN COUPLING [J].
BARFIELD, M ;
CHAKRABA.B .
CHEMICAL REVIEWS, 1969, 69 (06) :757-+
[3]  
Barone V., 1996, RECENT ADV DENSITY 1, V1
[4]   13C-1H and 13C-13C spin coupling behavior in aldofuranosyl rings from density functional theory [J].
Cloran, F ;
Carmichael, I ;
Serianni, AS .
JOURNAL OF PHYSICAL CHEMISTRY A, 1999, 103 (19) :3783-3795
[5]  
Contreras R. H., 1993, ANNU REP NMR SPECTRO, V27, P255
[6]   Advances in theoretical and physical aspects of spin-spin coupling constants [J].
Contreras, RH ;
Peralta, JE ;
Giribet, CG ;
De Azúa, MC ;
Facelli, JC .
ANNUAL REPORTS ON NMR SPECTROSCOPY, VOL 41, 2000, 41 :55-184
[7]  
CONTRERAS RH, 1990, J MOL STRUC-THEOCHEM, V69, P175, DOI 10.1016/0166-1280(90)80039-Q
[8]   Angular dependence of spin-spin coupling constants [J].
Contreras, RH ;
Peralta, JE .
PROGRESS IN NUCLEAR MAGNETIC RESONANCE SPECTROSCOPY, 2000, 37 (04) :321-425
[9]  
CONTRERAS RH, 1993, J MOL STRUC-THEOCHEM, V103, P249, DOI 10.1016/0166-1280(93)87009-3
[10]   Density functional calculation of 1JC-H coupling constants in cyclohexane and diheterocyclohexanes.: Repercussion of stereoelectronic effects on coupling constants [J].
Cuevas, G ;
Juaristi, E ;
Vela, A .
JOURNAL OF PHYSICAL CHEMISTRY A, 1999, 103 (07) :932-937