0000000001284783
AUTHOR
Neil Vasdev
NMR Spectroscopic Evidence for the Intermediacy of XeF3− in XeF2/F− Exchange, Attempted Syntheses and Thermochemistry of XeF3− Salts, and Theoretical Studies of the XeF3− Anion
The existence of the trifluoroxenate(II) anion, XeF(3)(-), had been postulated in a prior NMR study of the exchange between fluoride ion and XeF(2) in CH(3)CN solution. The enthalpy of activation for this exchange, ΔH(⧧), has now been determined by use of single selective inversion (19)F NMR spectroscopy to be 74.1 ± 5.0 kJ mol(-1) (0.18 M) and 56.9 ± 6.7 kJ mol(-1) (0.36 M) for equimolar amounts of [N(CH(3))(4)][F] and XeF(2) in CH(3)CN solvent. Although the XeF(3)(-) anion has been observed in the gas phase, attempts to prepare the Cs(+) and N(CH(3))(4)(+) salts of XeF(3)(-) have been unsuccessful, and are attributed to the low fluoride ion affinity of XeF(2) and fluoride ion solvation in…
NMR Spectroscopic Evidence for the Intermediacy of XeF3– in XeF2/F– Exchange, Attempted Syntheses and Thermochemistry of XeF3– Salts, and Theoretical Studies of the XeF3– Anion
The existence of the trifluoroxenate(II) anion, XeF3−, had been postulated in a prior NMR study of the exchange between fluoride ion and XeF2 in CH3CN solution. The enthalpy of activation for this exchange, ΔH⧧, has now been determined by use of single selective inversion 19F NMR spectroscopy to be 74.1 ± 5.0 kJ mol−1 (0.18 M) and 56.9 ± 6.7 kJ mol−1 (0.36 M) for equimolar amounts of [N(CH3)4][F] and XeF2 in CH3CN solvent. Although the XeF3− anion has been observed in the gas phase, attempts to prepare the Cs+ and N(CH3)4+ salts of XeF3− have been unsuccessful, and are attributed to the low fluoride ion affinity of XeF2 and fluoride ion solvation in CH3CN solution. The XeF3− anion would rep…
On the consensus nomenclature rules for radiopharmaceutical chemistry – Reconsideration of radiochemical conversion
Radiochemical conversion is an important term to be included in the "Consensus nomenclature rules for radiopharmaceutical chemistry". Radiochemical conversion should be used to define reaction efficiency by measuring the transformation of components in a crude reaction mixture at a given time, whereas radiochemical yield is better suited to define the efficiency of an entire reaction process including, for example, separation, isolation, filtration, and formulation. (C) 2020 Elsevier Inc. All rights reserved.