A theoretical and experimental study of the electric field and magnetic anisotropy effects on proton chemical shifts
Proton magnetic shielding constants are divided into different contributions using the IPPP technique (inner projections of the polarization propagator). Total magnetic shielding constants are calculated within the CHF-INDO-GIAO approach (coupled-Hartree-Fock-INDO-gauge-invariant atomic orbitals). I...
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| Autores principales: | , , , |
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| Formato: | JOUR |
| Acceso en línea: | http://hdl.handle.net/20.500.12110/paper_03010104_v118_n3_p325_Ferraro |
| Aporte de: |
| Sumario: | Proton magnetic shielding constants are divided into different contributions using the IPPP technique (inner projections of the polarization propagator). Total magnetic shielding constants are calculated within the CHF-INDO-GIAO approach (coupled-Hartree-Fock-INDO-gauge-invariant atomic orbitals). In order to compare the electric field and magnetic anisotropy effects of neighbouring groups, two model compounds were chosen, namely, ethyl cyanoformate, I, and ethylformate, II, which show to frozen and unequally populated rotamers each at room temperature. Their proton spectra were measured and the difference in shielding of methylene protons in each pair of rotamers was theoretically analysed with the abovementioned technique. The experimental difference in chemical shifts is quantitatively reproduced with the present analysis. © 1987. |
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