Conformational Analysis of 2-Formylselenophene by Means of 13C - 1H, 13C - 13C, and 77Se - 1H Spin - Spin Coupling Constants

2009 ◽  
Vol 62 (7) ◽  
pp. 734 ◽  
Author(s):  
Yury Yu. Rusakov ◽  
Leonid B. Krivdin ◽  
Natalia V. Istomina ◽  
Ekaterina P. Levanova ◽  
Galina G. Levkovskaya
Keyword(s):  
Conformational Analysis ◽  
Internal Rotation ◽  
Coupling Constants ◽  
Spin Coupling ◽  
Experimental Measurements ◽  
Formyl Group ◽  
Spin Coupling Constants ◽  
Spin Spin Coupling

Theoretical energy-based conformational analysis of 2-formylselenophene performed at the MP2/6–311G** level together with experimental measurements and SOPPA/aug-cc-pVTZ-J calculations of its 13C–1H, 13C–13C, and 77Se–1H spin–spin coupling constants showed that this compound predominantly adopts the s-cis conformation. Most of the spin–spin coupling constants under study, especially vicinal 77Se–1H couplings, demonstrate remarkable stereochemical behaviour with respect to the internal rotation of the formyl group, which is of major importance in stereochemical studies of the related selenium-containing compounds.

NMR spectra, MO calculations of spin-spin coupling constants and conformational analysis of substituted 1,3-dioxolanes

1980 ◽  
Vol 13 (1) ◽  
pp. 17-25 ◽  
Author(s):  
Rois Benassi ◽  
Luisa Schenetti ◽  
Ferdinando Taddei ◽  
Luigi Villa ◽  
Vincenzo Ferri
Keyword(s):  
Conformational Analysis ◽  
Nmr Spectra ◽  
Coupling Constants ◽  
Spin Coupling ◽  
Mo Calculations ◽  
Spin Coupling Constants ◽  
Spin Spin Coupling

13C-13C spin-spin coupling constants in structural studies: XL. Conformational analysis of N-vinylpyrroles

2007 ◽  
Vol 43 (6) ◽  
pp. 880-887 ◽  
Author(s):  
Yu. Yu. Rusakov ◽  
L. B. Krivdin ◽  
E. Yu. Shmidt ◽  
A. M. Vasil’tsov ◽  
A. I. Mikhaleva ◽  
...  
Keyword(s):  
Conformational Analysis ◽  
Coupling Constants ◽  
Spin Coupling ◽  
Structural Studies ◽  
Spin Coupling Constants ◽  
Spin Spin Coupling

1H nuclear magnetic resonance and molecular orbital studies of 2-formylstyrene. Three significant nonplanar conformers at 300 K

1995 ◽  
Vol 73 (12) ◽  
pp. 2208-2216 ◽  
Author(s):  
Ted Schaefer ◽  
Scott Kroeker ◽  
David M. McKinnon
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Molecular Orbital ◽  
Long Range ◽  
Coupling Constants ◽  
Spin Coupling ◽  
Formyl Group ◽  
Trans Conformer ◽  
Spin Coupling Constants ◽  
Spin Spin Coupling

The 1H nuclear magnetic resonance spectra of 2-formylstyrene, from dilute solutions in CS2–C6DI2 and acetone-d6, are analyzed to yield precise chemical shifts and spin–spin coupling constants. The long-range coupling constants imply a conformational distribution in which the O-trans conformer is 55% abundant in both polar and nonpolar environments. They also imply that the vinyl group, on average, is twisted out of the aromatic plane to a much larger extent than in styrene. The 6-31G* basis set gives an ab initio potential for the torsion of the vinyl moiety with a relatively deep minimum at 38° out-of-plane, for the O-cis conformer. For the O-trans conformer, two minima are found, one at 45° and another at 129.6°. Essentially the same potential is obtained with the 6-31G** basis. The latter corresponds to a close approach of the hydrogen atom of the formyl group and π orbitals or the β-carbon atom of the olefinic side chain. This local minimum is interesting in terms of a hypothesis used to explain the photochemistry of the molecule. The long-range coupling constants are consistent with the conformational properties calculated for the free molecule; they also indicate no significant difference between the conformational behaviour of the molecule in the two solvents. A proximate coupling constant of −0.16 Hz exists between the formyl and methine (α) protons. The latter is strongly deshielded in the presence of the formyl group, so that it becomes even less shielded than some of the aromatic protons. Keywords: 1H NMR, 2-formylstyrene (o-vinylbenzaldehyde); long-range spin–spin coupling constants, 2-formylstyrene; conformations, three nonplanar of 2-formylstyrene; molecular orbital calculations, conformations of 2-formylstyrene.

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