Chlorine pentafluoride is an interhalogen compound with formula . This colourless gas is a strong oxidant that was once a candidate oxidizer for rockets. The molecule adopts a square pyramidal structure with C<sub>4v</sub> symmetry, as confirmed by its high-resolution <sup>19</sup>F NMR spectrum. It was first synthesized in 1963.
Preparation
Some of the earliest research on the preparation was classified. It was first prepared by fluorination of chlorine trifluoride at high temperatures and high pressures:
Certain metal fluorides, , e.g. (potassium tetrafluorochlorate(III)), (rubidium tetrafluorochlorate(III)), (caesium tetrafluorochlorate(III)), react with to produce and the corresponding alkali metal fluoride.
:
It is also a strong fluorinating agent. At room temperature it reacts readily with all elements (including otherwise "inert" elements like platinum and gold) except noble gases, nitrogen, oxygen and fluorine.
Chlorine pentafluoride reacts violently with water or moisture in the air and even water ice at (to produce corrosive hydrofluoric acid and toxic chlorine gas), nitric acid (even at −100 °C), metals and organic materials. It is a strong oxidizer. It does not burn, but supports burning. On catching fire or heated to decomposition, it emits corrosive and very toxic gases. Vapors from liquefied gas are initially heavier than air and spread along the floor. These are strong oxidizers and will react vigorously or explosively with many materials including fuels. May ignite flammable materials (wood, paper, oil, clothing, etc.).