Compounds of fluorine heavier halogens (chlorine, bromine, and iodine) all form mono-, tri-, and pentafluorides: XF, XF, and XF. Of the neutral +7 species, only iodine heptafluoride is known. While chlorine and bromine heptafluorides are not known, the corresponding cations and , extremely strong oxidizers, are. Astatine is not well-studied, and although there is a report of a non-volatile astatine monofluoride, its existence is debated. Many of the halogen fluorides are powerful fluorinators. Chlorine trifluoride is particularly noteworthy—readily fluorinating asbestos and refractory oxides—and may be even more reactive than chlorine pentafluoride. Used industrially, ClF requires special precautions similar to those for fluorine gas
Fluorine perchlorate in a rare oxidation state of 0, due to the electronegativity of oxygen, which is higher than that of chlorine but lower than that of fluorine. FClO has a very dangerous and unpredictable series of reactions associated with it, as a covalent perchlorate (chlorine in the +7 oxidation state) and a compound featuring a very sensitive O-F single bond. Small amounts of reducing agent, such as organic compounds, can trigger explosive detonation. Products of these decomposition reactions could include oxygen halides, interhalogen compounds, and other hazardous substances. Accidental synthesis is possible if precursors are carelessly mixed. Like similar covalent fluorides