Proton deshielding by spatial proximity: An experimental and theoretical study for ortho‐substituted anisoles
A quantitative estimation of the proton deshielding effect produced by a sterically crowded environment was obtained experimentally, based on departures from the chemical shift additivity rule of protons ortho to OCH3 and NO2 groups in benzene derivatives, where a conformational change from these si...
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| Autores principales: | , , , |
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| Formato: | JOUR |
| Acceso en línea: | http://hdl.handle.net/20.500.12110/paper_07491581_v23_n5_p296_Contreras |
| Aporte de: |
| Sumario: | A quantitative estimation of the proton deshielding effect produced by a sterically crowded environment was obtained experimentally, based on departures from the chemical shift additivity rule of protons ortho to OCH3 and NO2 groups in benzene derivatives, where a conformational change from these side‐chain groups is expected. The influences of these conformational changes were also analysed from a theoretical point of view. Calculations of the magnetic shielding tensor were carried out at the INDO approximation with gauge invariant atomic orbitals, together with the uncoupled Hartree‐Fock approach. Theoretical results for these proton deshielding effects are in very good agreement with those determined experimentally. Copyright © 1985 John Wiley & Sons, Ltd. |
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