Chlorine pentafluoride

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_4v symmetry, as confirmed by its high-resolution ¹⁹F 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:
[Nickel(II) fluoride|] catalyzes this reaction.
Certain metal fluorides,, e.g.,,, react with to produce and the corresponding alkali metal fluoride.

Reactions

In a highly exothermic reaction, reacts with water to produce chloryl fluoride and hydrogen fluoride:
It is also a strong fluorinating agent. At room temperature it reacts readily with all elements except noble gases, nitrogen, oxygen and fluorine.

Uses

Rocket propellant

Chlorine pentafluoride was once considered for use as an oxidizer for rockets. As a propellant, it has a higher maximum specific impulse than [Chlorine trifluoride|], but with the same difficulties in handling. Due to the hazardous nature of chlorine pentafluoride and the large amounts of hydrogen fluoride in the exhaust, it has yet to be used in a large scale rocket propulsion system.

Safety

Chlorine pentafluoride is highly toxic. It is a strong irritant to skin, eyes and mucous membranes. It is very corrosive. Causes severe and painful skin, eye and respiratory tract burns. May cause lung damage, toxic pneumonitis and permanent blindness. It is fatal if inhaled or absorbed through skin. Containers with chlorine pentafluoride may explode when heated. Ruptured cylinders may rocket violently. Chlorine pentafluoride causes other symptoms like nausea, vomiting and dyspnea.
Chlorine pentafluoride reacts violently with water or moisture in the air and even water ice at, nitric acid, 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.