Analysis of the Electronic Origin of the (1)J(CH) Spin-Spin Coupling Trend in 1-X-Cyclopropanes: Experimental and DFT Study

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)A conceptual analysis of the CLOPPA (Contributions from Localized Orbitals within the Polarization Propagator Approach) expressions that deconvolute NMR spin-spin coupling constants [Diz A. C.; Giribet C. G.; Ruiz de Azua, M. C.; Contreras, R. H. Int. J. Quantum Chem. 1990, 37, 663.] into orbital contributions can provide an in-depth insight into the features of the electronic molecular structure that originate a given (1)J(CH) experimental trend. In this work, several 1-X-cyclopropane derivatives are taken as model compounds to apply such ideas to rationalize substituent effects on the Fermi contact term Of (1)J(CLH) spin-spin coupling. It is shown that in this type of coupling, its experimental trend, as measured in this work, cannot be accounted for with only the "bond" and the "other bond" contributions, requiring the inclusion of "other antibonding contributions". Such effect is discussed in terms of hyperconjugative interactions.112461195611959Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)CONICET [PIP 5119/05]UBACYT [X222]Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)FAPESP [06/03980-2, 05/59649-0]CONICET [PIP 5119/05]UBACYT [X222