The NMR shifts are not a measure for the nakedness of the fluoride anion

Computational 19F NMR. 1. General features

“…This is not unreasonable, in view of the polarizability of fluorine and its exposure to solvent in most molecules; on the other hand, the vast majority of data presented here pertain to weakly polar molecules, whose data were collected in non-polar solvents. In such cases, continuum solvent models are known to provide extremely small effects, whereas calculations on the fluoride anion solvated by various molecules show some 70-ppm variability in d(F -) [112]. While the case of F -may be an anomalously high value for solvent effects, this issue is clearly an open one.…”

Dissolution and Gelation of Cellulose in TBAF/DMSO Solutions: The Roles of Fluoride Ions and Water

“…F -· · · H binding lengths (where H derives from the solvent) in DMSO and water have been estimated to 1.876 and 1.415 Å, respectively. 30 By comparing the trend in δ (F-) with increasing water content to the values in the pure solvents, that is, -73 ppm in DMSO and -119 ppm in water, 31 one can indeed see that the local environment of the fluoride ion becomes significantly more aqueous-like. It is interesting to find that the functional form of the chemical shift dependence of the water signal, as observed by 1 H NMR (Figure 6a), closely resembles that of the fluoride signal in 19 F NMR.…”

Solid state nuclear magnetic resonance as a tool to explore solvent-free MALDI samples

“…The main 19 F resonance observed at Ϫ110 ppm ( Figure 1c) actually consists of two overlapping signals, one of which is particularly broad and reflects a large distribution of the chemical shift, suggesting a substantial participation of atmospheric water molecules in the reaction [37]. The 133 Cs MAS NMR spectrum still exhibits a typical signal of Cs ϩ coordinated with multiple oxygen atoms [31], but the chemical shift observed for this Form II is weakly down-fielded compared with Form I (Ϫ5 ppm versus Ϫ11 ppm, respectively).…”