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Institute
Ab-initio study and semiempirical calculations of keto-enol tautomerism of triazolopyrimidines
(1995)
1H, 13C, and 15N NMR study of the solution structure of metabridged bis(benzo-15-crown-5-ether)s
(1995)
NMR spectroscopic and theoretical structural analysis of 5,5-disubstituted hydantoins in solution
(1997)
Study of the tautomerism by experimentally and theoretically estimated 13C and 15N chemical shifts
(1997)
NMR spectroscopic and theoretical structural analysis of 5,5-disubstituted hydantoins in solution
(1997)
Competitive resonance at the carbonyl group as visualized by the natural bond orbital analysis
(1997)
Configuration and stereodynamics of exo/endoisomeric push-pull alkenes of pentadiene structure
(1998)
The influence of structure and lipophilicity of hydantoin derivatives on anticonvulsant activity
(1999)
NMR spectroscopic and ab-initio MO study of sterically hindered 2,3-disubstituted quinoxalines
(1999)
(3)J(C,H) coupling constants via a sulfur atom in two series of compounds, both including a sulfide, a sulfoxide and a sulfone, were detected experimentally and calculated by quantum mechanical methods. In the first series (1-3) the coupling between a hydrogen, bonded to an Sp(3) carbon, and an Sp(2) carbon is treated; the second series (4- 6) deals with the coupling between a hydrogen, bonded to an Sp3 carbon, and an Sp3 carbon. Different pulse sequences (broadband HMBC, SelJres, 1D HSQMBC, J-HMBC-2, selective J-resolved long-range experiment and IMPEACH-MBC) proved to be useful in determining the long-range (3)J(C,H) coupling constants. However, the dynamic behaviour of two of the compounds (4 and 6) led to weighted averages of the two coupling constants expected (concerning equatorial and axial positions of the corresponding hydrogens). DFT calculations proved to be useful to calculate not only the (3)J(C,H) coupling constants but also the different contributions of FC, PSO, DSO and SD terms; the calculation of the Fermi contact term (FC) was found to be sufficient for the correct estimation of (3)J(C,H) coupling constants. Copyright (C) 2004 John Wiley Sons, Ltd
The C-13 chemical shifts of 20 rigid bicyclic compounds have been calculated with ab initio HF and MP2 methods. The calculations showed very good reproducibility of the experimental values. The molecular orbital interactions in the rigid, nearly planar delta-syn-axial fragments in the isomeric groups of norbornane derivatives 1.x-4.x were studied in detail and were employed to explain the deshielding delta-syn-axial effect in C-13 NMR spectroscopy. (C) 2004 Elsevier B.V. All rights reserved