The fluoronium ion is an

inorganic In chemistry, an inorganic compound is typically a chemical compound that lacks carbon–hydrogen bonds, that is, a compound that is not an organic compound. The study of inorganic compounds is a subfield of chemistry known as '' inorganic chemist ...

cation An ion () is an atom or molecule with a net electrical charge. The charge of an electron is considered to be negative by convention and this charge is equal and opposite to the charge of a proton, which is considered to be positive by convent ...

with the

chemical formula In chemistry, a chemical formula is a way of presenting information about the chemical proportions of atoms that constitute a particular chemical compound or molecule, using chemical element symbols, numbers, and sometimes also other symbols, ...

. It is one of the cations found in

fluoroantimonic acid Fluoroantimonic acid is a mixture of hydrogen fluoride and antimony pentafluoride, containing various cations and anions (the simplest being and ). This substance is a superacid that can be over a billion times stronger than 100% pure sulfuri ...

. The structure of the salt with the anion, has been determined. The fluoronium ion is

isoelectronic Isoelectronicity is a phenomenon observed when two or more molecules have the same structure (positions and connectivities among atoms) and the same electronic configurations, but differ by what specific elements are at certain locations in the ...

with the

water Water (chemical formula ) is an inorganic, transparent, tasteless, odorless, and nearly colorless chemical substance, which is the main constituent of Earth's hydrosphere and the fluids of all known living organisms (in which it acts as a ...

molecule and the azanide ion. The term can also refer to organyl substituted species of type H––R, R––R, or R₂C=F⁺. In contrast to the heavier halogens, which have long been known to form open-chain

halonium ion A halonium ion is any onium ion containing a halogen atom carrying a positive charge. This cation has the general structure where X is any halogen and no restrictions on R, this structure can be cyclic or an open chain molecular structure. Halo ...

s (such as e₂Clsup>+ l(OTeF₆)₄sup>–) as well as cyclic haliranium ions, fluorine was not believed to form fluoronium ions of type R––R until the recent characterization of a fluoronium ion locked in a designed cage structure by Lectka and coworkers. Recent solvolysis experiments and NMR spectroscopic studies on a metastable –F–Csup>+ fluoronium ion strongly support the divalent fluoronium structure over the alternative rapidly equilibrating classical carbocation. Definitive structural proof of the symmetrical –F–Csup>+ was reported by Riedel, Lectka, and coworkers by single crystal X-ray diffraction analysis. Besides its synthesis and crystallographic characterization as the b₂F₁₁sup>− salt, vibrational spectra could be recorded and a detailed analysis concerning the nature of the bonding situation in this fluoronium ion and its heavier halonium homologues was reported.

References

{{reflist Cations Fluorine compounds Hydrogen compounds