Evidence for a steric effect on directly bonded carbon-fluorine and carbon-proton nuclear magnetic resonance couplings

Analysis of CF···FC Interactions on Cyclohexane and Naphthalene Frameworks

“…Based on the well known angular and distance dependence of CFFC interactions and J FF SSCCs, 39 Mallory et al, 40,41 proposed a lone-pair overlap theory, according to This model can explain "through-space" SSCCs, but does not assess fluorinefluorine interactions as repulsive or attractive. 40 They can be either, as shown by the results for the CH 4-x F x dimers ( Figure S7).…”

Experimental and quantum chemical investigation of the stereochemical dependence of spin coupling constants in symmetrical strained alkenes

“…One bond 13 C-1 H and three-bond H-H spin coupling constants for 3 and 4 have been determined before, 11 -14 and efforts were made to correlate changes in the 13 C and 1 H NMR spectral parameters with strain-induced changes in geometry and hybridization. However, no clear correlation was found for the 13 C chemical shifts or the 13 C-1 H coupling constants. 13 Compounds 1-4 are symmetrical with respect to the double bond and therefore the spin-spin coupling between the olefinic carbon atoms cannot be observed in normal NMR spectra.…”

13C19F spin–spin coupling in some monofluoro‐substituted polycyclic aromatic hydrocarbons

“…In order to rationalize that I'.T(C, F)pen\ > I'J(C, F)otherl Manatt er a1. 24 have proposed that steric effects may increase the numerical magnitude of onebond l3C-I9F couplings. This explanation also accounts qualitatively for the differences observed in the magnitudes of 'J(C,F) in 1-3, 5-9, and 11-16.…”