Analysis of the phosphorus lone-pair orientational effect on 31P13C couplings in 7-(phosphamethyl)norbornene
An IPPP-INDO analysis of PC couplings is carried out in 7-(phosphamethyl) norbornene for the anti and syn conformations. A strong orientational effect of the P lone pair is expected to be responsible for the differences in the coupling values between conformations. Total couplings are decomposed int...
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| Autores principales: | , , , |
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| Publicado: |
1988
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| Acceso en línea: | https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_01661280_v164_n1-2_p1_Aucar http://hdl.handle.net/20.500.12110/paper_01661280_v164_n1-2_p1_Aucar |
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| Sumario: | An IPPP-INDO analysis of PC couplings is carried out in 7-(phosphamethyl) norbornene for the anti and syn conformations. A strong orientational effect of the P lone pair is expected to be responsible for the differences in the coupling values between conformations. Total couplings are decomposed into through-space and through-bond components. Further analysis of the through-space Fermi contact term is carried out by resolving it into contributions given by different "through-space coupling pathways", each pathway being defined by excitations which are amenable to direct analysis using the inner-projected polarization propagator technique. The experimental trends of PC couplings in both conformations are closely reproduced. The differences between both conformations are found to be ruled by: (i) the orientation of the P lone pair, which is shown to be an efficient means of transmitting the spin information; (ii) the transmission through the CH rear lobe; and (iii) the orientational effect of the PC antibonding molecular orbital. From (iii) the important role played by vacant molecular orbitals is also brought to attention. © 1988. |
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