Chlorine trifluoride

Chlorine trifluoride is an interhalogen compound with the formula ClF₃. This colourless, poisonous, corrosive, and extremely reactive gas condenses to a pale-greenish yellow liquid, the form in which it is most often sold (pressurized at room temperature). The compound is primarily of interest as a component in rocket fuels, in plasmaless cleaning and etching operations in the semiconductor industry, in nuclear reactor fuel processing, and other industrial operations.

Preparation, structure, and properties

It was first reported in 1930 by Ruff and Krug who prepared it by fluorination of chlorine; this also produced ClF and the mixture was separated by distillation.

ClF₃ is approximately T-shaped, with one short bond (1.598 Å) and two long bonds (1.698 Å). This structure agrees with the prediction of VSEPR theory, which predicts lone pairs of electrons as occupying two equatorial positions of a hypothetic trigonal bipyramid. The elongated Cl-F axial bonds are consistent with hypervalent bonding.

Chlorine pentafluoride

Chlorine pentafluoride is an interhalogen compound with formula ClF₅. This colourless gas is an 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.

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:

NiF₂ catalyzes this reaction.

Certain metal fluorides, MClF₄ (i.e. KClF₄, RbClF₄, CsClF₄) react with F₂ to produce ClF₅ and the corresponding alkali metal fluoride.

Reactions

In a highly exothermic reaction, water hydrolyses ClF₅ 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.

See also

References

External links

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