hexafluorobenzene

Hexafluorobenzene, HFB or perfluorobenzene is an organofluorine compound with the chemical formula . In this derivative of benzene, all hydrogen atoms have been replaced by fluorine atoms. The technical uses of the compound are limited, although it has some specialized uses in the laboratory owing to distinctive spectroscopic properties.

== Geometry of the aromatic ring == Hexafluorobenzene stands somewhat aside in the perhalogenbenzenes. If a perhalogenated benzene ring were to remain planar, then geometric constraints would force adjacent halogens closer than their associated nonbonding radius. Consequently the benzene ring buckles, reducing p-orbital overlap and aromaticity to avoid the steric clash. Perfluorobenzene is an exception: as shown in the following table, two fluorines are small enough to avoid collision, retaining planarity and full aromaticity. {| class="wikitable" ! Formula ! Name ! Inter-halogen distance (if planar) ! Nonbonding radius×2 ! Consequent symmetry |- | C6F6 || Hexafluorobenzene || 279 pm || 270 pm || D6h |- | C6Cl6 || Hexachlorobenzene || 312 pm || 360 pm || D3d |- | C6Br6 || Hexabromobenzene || 327 pm || 390 pm || D3d |- | C6I6 || Hexaiodobenzene || 354 pm || 430 pm || D3d |}