| Full text | |
| Author(s): |
Contreras, Ruben H.
;
dos Santos, Francisco P.
;
Ducati, Lucas C.
;
Tormena, Claudio F.
Total Authors: 4
|
| Document type: | Journal article |
| Source: | Magnetic Resonance in Chemistry; v. 48, p. 8-pg., 2010-12-01. |
| Abstract | |
Adequate analyses of canonical molecular orbitals (CMOs) can provide rather detailed information on the importance of different sigma-Fermi contact (FC) coupling pathways (FC term transmitted through the sigma-skeleton). Knowledge of the spatial distribution of CMOs is obtained by expanding them in terms of natural bond orbitals (NBOs). Their relative importance for transmitting the sigma-FC contribution to a given spin-spin coupling constants (SSCCs) is estimated by resorting to the expression of the FC term given by the polarisation propagator formalism. In this way, it is possible to classify the effects affecting such couplings in two different ways: delocalisation interactions taking place in the neighbourhood of the coupling nuclei and 'round the ring' effects. The latter, associated with sigma-ring currents, are observed to yield significant differences between the FC terms of (2)J(C2H3) and (2)J(C3H2) SSCCs which, consequently, are taken as probes to gauge the differences in sigma-ring currents for the five-membered rings (furan, thiophene, selenophene and pyrrol) and also for the six-membered rings (benzene, pyridine, protonated pyridine and N-oxide pyridine) used in the present study. Copyright (C) 2010 John Wiley & Sons, Ltd. (AU) | |
| FAPESP's process: | 08/06282-0 - Transmission mechanism of scalar spin-spin coupling constants involving fluorine atom. |
| Grantee: | Roberto Rittner Neto |
| Support Opportunities: | Regular Research Grants |
| FAPESP's process: | 05/59649-0 - Conformational equilibria studies by nuclear magnetic resonance spectroscopy, infrared spectroscopy and theoretical calculations |
| Grantee: | Roberto Rittner Neto |
| Support Opportunities: | Research Projects - Thematic Grants |
| FAPESP's process: | 09/07765-7 - Experimental and theoretical studies of nJCH coupling constants |
| Grantee: | Francisco Paulo dos Santos |
| Support Opportunities: | Scholarships in Brazil - Post-Doctoral |