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The electronic origin of unusually large n J FN coupling constants in some fluoroximes
Author(s) -
Favaro Denize C.,
Contreras Rubén H.,
Tormena Cláudio F.
Publication year - 2013
Publication title -
magnetic resonance in chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.483
H-Index - 72
eISSN - 1097-458X
pISSN - 0749-1581
DOI - 10.1002/mrc.3950
Subject(s) - chemistry , coupling constant , natural bond orbital , atomic orbital , lone pair , coupling (piping) , electronic structure , atomic physics , computational chemistry , fluorine , space (punctuation) , electron , crystallography , molecular physics , density functional theory , quantum mechanics , physics , molecule , mechanical engineering , linguistics , philosophy , organic chemistry , engineering
SOPPA(CCSD) calculations show that the FC term is the most important contribution to the through‐space transmission of J FN coupling constants for the fluoroximes studied in this work. Because of the well‐known behavior of FC term, a new rationalization for the experimental TS J FN SSCC is presented. It is mainly based on the overlap matrix ( S ij ) between fluorine and nitrogen lone pairs obtained from NBO analyses. An expression is proposed to take into account the influence of the electronic density ( D ij ) between coupled nuclei as well as the s% character at the site of the coupling nuclei of bonds and non‐bonding electron pairs involved in D ij . In using this approach, a linear correlation between TS J FN versus D ij is obtained. The most important aspect of this rationalization is related to the facility for understanding the behavior of some unusual experimental coupling constants. It is shown that, at least in this case, the electronic origin of the so‐called through‐space coupling is transmitted through to the overlap of orbitals on the coupled atoms, suggesting that, at least for these compounds, instead of through‐space coupling, it should better be dubbed as ‘through overlapping orbital coupling’. Copyright © 2013 John Wiley & Sons, Ltd.