Theoretical comparison of proximate peri and ortho substituent effects on proton chemical shifts
The magnetic shielding of the peri proton in 1-X-naphthalenes and the ortho proton in 1-X-benzenes were studied and compared. The respective distances between the substituent group X and the peri proton in 1-X-naphthalenes or the ortho proton in 1-X-benzenes are very similar, but the substituent che...
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| Autores principales: | , , |
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| Formato: | JOUR |
| Acceso en línea: | http://hdl.handle.net/20.500.12110/paper_01661280_v254_nC_p253_Herr |
| Aporte de: |
| Sumario: | The magnetic shielding of the peri proton in 1-X-naphthalenes and the ortho proton in 1-X-benzenes were studied and compared. The respective distances between the substituent group X and the peri proton in 1-X-naphthalenes or the ortho proton in 1-X-benzenes are very similar, but the substituent chemical shifts may be very different, depending on the substituent. In 1-X-naphthalenes the C-H8 (peri proton) bond takes an orientation which is different from that adopted by the C-H2 (ortho proton) bond in 1-X-benzenes. This may be responsible for the observed differences, so we evaluated the "throughspace" contributions to the magnetic shielding in both cases within the IPPP-CHF-INDO-GIAO (inner projections of the polarization propagator, coupled Hartree-Fock, semiempirical INDO wave function, gauge invariant atomic orbitals) approach to investigate the extent to which these effects determine the experimental trends. © 1992. |
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