Spin-spin coupling across intramolecular N-H(+)-N hydrogen bonds in models for proton sponges : an ab initio investigation
2008 John Wiley & Sons, Ltd.
| Veröffentlicht in: | Magnetic resonance in chemistry : MRC. - 1985. - 46(2008), 5 vom: 05. Mai, Seite 457-63 |
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| Weitere Verfasser: | , |
| Format: | Online-Aufsatz |
| Sprache: | English |
| Veröffentlicht: |
2008
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| Zugriff auf das übergeordnete Werk: | Magnetic resonance in chemistry : MRC |
| Schlagworte: | Journal Article Research Support, Non-U.S. Gov't Protons Spin Labels Hydrogen 7YNJ3PO35Z Nitrogen N762921K75 |
| Zusammenfassung: | 2008 John Wiley & Sons, Ltd. Ab initio calculations have been performed to obtain structures and coupling constants (1)J(N-H), (1h)J(H-N), and (2h)J(N-N) for models of proton sponges with symmetric and asymmetric N-H(+)-N intramolecular hydrogen bonds (IMHBs). For a given model, the asymmetric structure has a lower energy, a longer N-N distance, and a hydrogen bond which has a greater deviation from linearity. The computed values of (2h)J(N-N) for the models are significantly less than predicted values based on the distance dependence of (2h)J(N-N) for complexes with intermolecular N-H(+)-N hydrogen bonds. However, the reduced values of (2h)J(N-N) cannot be attributed solely to the distortion of the hydrogen bond in the models, but also reflect differences in s electron populations at the nitrogens in both the ground state and the excited states which couple to it through the Fermi-contact (FC) operator. Values of (2h)J(N-N) for IMHBs can be related quadratically to the N-N distances in the models, and demonstrate that there is no discrepancy between computed values of (2h)J(N-N) at the short N-N distances found in these systems and experimental data for proton sponges |
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| Beschreibung: | Date Completed 20.05.2008 Date Revised 21.11.2013 published: Print Citation Status MEDLINE |
| ISSN: | 1097-458X |
| DOI: | 10.1002/mrc.2199 |