INVESTIGADORES
AUCAR gustavo Adolfo
artículos
Título:
ANALYSIS OF MULTIPATH TRANSMISSION OF SPIN-SPIN COUPLING CONSTANTS IN l-X-BICYCLOALKANES P
Autor/es:
GUSTAVO A. AUCAR; VERÓNICA ZUNINO; MARTA B FERRARO; CLAUDIA G. GIRIBET; MARTÍN RUIZ DE AZÚA; RUBÉN H. CONTRERAS
Revista:
JOURNAL OF MOLECULAR STRUCTURE THEOCHEM
Editorial:
ELSEVIER SCIENCE BV
Referencias:
Lugar: Amsterdam; Año: 1990 vol. 205 p. 63 - 77
ISSN:
0166-1280
Resumen:
The through-space transmission of couplings involving bridgehead carbon atoms in substituted l-X-bicycloalkanes (X=H, F, CH3) was analysed theoretically with a modified version of the IPPP-INDO method. The through-space components are further decomposed into a sum of individual "coupling pathways", each of which involves two occupied and two vacant localized orbitals. The relative importance of these orbitals indicates which are the most important bonds and antibonding orbitals defining the transmission mechanisms. In this way, it is shown that the main trends of the through-space component of J(CI-H) (where H is the proton bonded to the remaining bridgehead carbon atom CH) and J(CI-CH) are directly related to the mplitude of the CH-H bonding orbital on Cl. The decrease in the through-space values when going from bicyclopentane to bicyclooctane is thus explained by the decrease in this amplitude as the Cl-CH distance increases. The dependence of J(CI-H) on the substituent X can also be explained by the effect of X on the CH-H bond. The through-space IPPP results are found to be quite different from those obtained using the NNBI approach, showing that both methods are based on different grounds.