Editing Fluoride (section)

===Naked fluoride===
Most fluoride salts dissolve to give the bifluoride ({{chem|HF|2|-}}) anion. Sources of true F<sup>−</sup> anions are rare because the highly basic fluoride anion abstracts protons from many, even adventitious, sources. Relative [[solvation|unsolvated]] fluoride, which does exist in aprotic solvents, is called "naked". '''Naked fluoride''' is a strong [[Lewis base]],<ref>{{cite journal |last1=Schwesinger |first1=Reinhard |last2=Link |first2=Reinhard |last3=Wenzl |first3=Peter |last4=Kossek |first4=Sebastian |title=Anhydrous Phosphazenium Fluorides as Sources for Extremely Reactive Fluoride Ions in Solution |journal=Chemistry: A European Journal |volume=12 |issue=2 |pages=438–45 |year=2005 |pmid=16196062 |doi=10.1002/chem.200500838 }}</ref> and a powerful nucleophile. Some quaternary ammonium salts of naked fluoride include [[tetramethylammonium fluoride]]  and [[tetrabutylammonium fluoride]].<ref name=dimagno>{{cite journal |author1=Haoran Sun |author2=Stephen G. DiMagno |name-list-style=amp | title= Anhydrous Tetrabutylammonium Fluoride | journal= [[Journal of the American Chemical Society]] | year= 2005 | volume= 127 | pages= 2050–1| doi=10.1021/ja0440497 | pmid= 15713075 | issue= 7}}</ref> [[Cobaltocenium]] fluoride is another example.<ref>{{cite journal |doi=10.1021/ja00103a045|title=Cobaltocenium Fluoride: A Novel Source of "Naked" Fluoride Formed by Carbon-Fluorine Bond Activation in a Saturated Perfluorocarbon|year=1994|last1=Bennett|first1=Brian K.|last2=Harrison|first2=Roger G.|last3=Richmond|first3=Thomas G.|journal=Journal of the American Chemical Society|volume=116|issue=24|pages=11165–11166}}</ref> However, they all lack structural characterization in aprotic solvents. Because of their high basicity, many so-called naked fluoride sources are in fact bifluoride salts. In late 2016 [[imidazolium]] fluoride was synthesized that is the closest approximation of a thermodynamically stable and structurally characterized example of a "naked" fluoride source in an aprotic solvent (acetonitrile).<ref>{{cite journal | last1 = Alič | first1 = B. | last2 = Tavčar | first2 = G. | year = 2016 | title = Reaction of N-heterocyclic carbene (NHC) with different HF sources and ratios – A free fluoride reagent based on imidazolium fluoride | journal = J. Fluorine Chem. | volume = 192 | pages = 141–146 | doi = 10.1016/j.jfluchem.2016.11.004 }}</ref> The sterically demanding imidazolium cation stabilizes the discrete anions and protects them from polymerization.<ref>{{cite journal | last1 = Alič | first1 = B. | last2 = Tramšek | first2 = M. | last3 = Kokalj | first3 = A. | last4 = Tavčar | first4 = G. | year = 2017| title = Discrete GeF5– Anion Structurally Characterized with a Readily Synthesized Imidazolium Based Naked Fluoride Reagent | journal = Inorg. Chem. | volume = 56 | issue = 16| pages = 10070–10077 | doi = 10.1021/acs.inorgchem.7b01606 | pmid = 28792216 }}</ref><ref>{{cite journal | last1 = Zupanek | first1 = Ž. | last2 = Tramšek | first2 = M. | last3 = Kokalj | first3 = A. | last4 = Tavčar | first4 = G. | year = 2018| title = Reactivity of VOF3 with N-Heterocyclic Carbene and Imidazolium Fluoride: Analysis of Ligand–VOF3 Bonding with Evidence of a Minute π Back-Donation of Fluoride | journal = Inorg. Chem. | volume = 57 | issue = 21| pages = 13866–13879 | doi = 10.1021/acs.inorgchem.8b02377 | pmid = 30353729 | s2cid = 53031199 }}</ref>