IMIT   21220
INSTITUTO DE MODELADO E INNOVACION TECNOLOGICA
Unidad Ejecutora - UE
artículos
Título:
Stereochemical dependence of NMR geminal spinspin coupling constants
Autor/es:
RUBEN H. CONTRERAS; PATRICIO F. PROVASI; FRANCISCO P. DOS SANTOS; CLAUDIO F. TORMENA
Revista:
MAGNETIC RESONANCE IN CHEMISTRY
Editorial:
John Wiley & Sons, Ltd.
Referencias:
Año: 2008 vol. 47 p. 113 - 120
ISSN:
0749-1581
Resumen:
In this work it was sought to explore the versatility of geminal spinspin coupling constants, 2JXY SSCCs, as probes forstereochemical studies. A set of compounds, where their experimental 2JXY SSCCs through the XCY molecular fragment arepredicted to be sensitive to hyperconjugative interactions involving either bonding or antibonding orbitals containing the Ccarbon atom (coupling pathway), were analyzed. SSCC calculations were performed for some selected examples using thesecond order polarization propagator approximation (SOPPA)method or within the DFT-B3LYP framework. Hyperconjugativeinteractions were calculated within the Natural Bond Orbital (NBO) approach. Results are condensed in two qualitative rules:Rule IM hyperconjugative interactions transferring charge into the coupling pathway yield a positive increase to the Fermicontact (FC), contribution to 2KXY reduced spinspin coupling constants (RSSCC), and Rule IIM hyperconjugative interactionstransferring charge from the coupling pathway yield a negative increase to the FC contribution to 2KXY RSSCC.