Chlorine pentafluoride

Chemical compound

Identifiers

CAS Number

13637-63-3^Y

3D model (JSmol)

Interactive image

ChemSpider

55559^N

ECHA InfoCard

100.033.734

PubChem CID

61654

RTECS number

FO2975000

UNII

O4RJ1HW01H^Y

CompTox Dashboard (EPA)

DTXSID90894056

InChI

InChI=1S/ClF5/c2-1(3,4,5)6^N
Key: KNSWNNXPAWSACI-UHFFFAOYSA-N^N

SMILES

FCl(F)(F)(F)F

Properties

Chemical formula

ClF₅

Molar mass

130.445 g mol⁻¹

Appearance

colorless gas

Density

4.5 kg/m³ (g/L)

Melting point

−103 °C (−153 °F; 170 K)

Boiling point

−13.1 °C (8.4 °F; 260.0 K)

Solubility in water

Hydrolyzes

Structure

Molecular shape

Square pyramidal

Thermochemistry

Std molar
entropy (S^⦵₂₉₈)

310.73 J K⁻¹ mol⁻¹

Std enthalpy of
formation (Δ_fH^⦵₂₉₈)

−238.49 kJ mol⁻¹

Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).

N verify (what is ^YN ?)

Infobox references

Chemical compound

Chlorine pentafluoride is an interhalogen compound with formula ClF₅. 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,^[1] as confirmed by its high-resolution ¹⁹F NMR spectrum.^[2] It was first synthesized in 1963.^[3]

Preparation

Some of the earliest research on the preparation was classified.^[4]^[5] It was first prepared by fluorination of chlorine trifluoride at high temperatures and high pressures:^[4]

ClF₃ + F₂ → ClF₅

ClF + 2F₂ → ClF₅

Cl₂ + 5F₂ → 2ClF₅

CsClF₄ + F₂ → CsF + ClF₅

NiF₂ catalyzes this reaction.^[6]

Certain metal fluorides, MClF₄ (i.e. KClF₄, RbClF₄, CsClF₄), react with F₂ to produce ClF₅ and the corresponding alkali metal fluoride.^[5]

Reactions

In a highly exothermic reaction, ClF₅ reacts with water to produce chloryl fluoride and hydrogen fluoride:^[7]

ClF
₅ + 2 H
₂O → ClO
₂F + 4 HF

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.^[2]

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 ClF₃, but with the same difficulties in handling.^[4] Due to the hazardous nature of chlorine pentafluoride, it has yet to be used in a large scale rocket propulsion system.

References

^ Greenwood, Norman N.; Earnshaw, Alan (1997). Chemistry of the Elements (2nd ed.). Butterworth-Heinemann. p. 833. ISBN 978-0-08-037941-8.
^ ^a ^b Pilipovich, D.; Maya, W.; Lawton, E.A.; Bauer, H.F.; Sheehan, D. F.; Ogimachi, N. N.; Wilson, R. D.; Gunderloy, F. C.; Bedwell, V. E. (1967). "Chlorine pentafluoride. Preparation and Properties". Inorganic Chemistry. 6 (10): 1918. doi:10.1021/ic50056a036.
^ Smith D. F. (1963). "Chlorine Pentafluoride". Science. 141 (3585): 1039–1040. Bibcode:1963Sci...141.1039S. doi:10.1126/science.141.3585.1039. PMID 17739492. S2CID 39767609.
^ ^a ^b ^c Clark, John Drury (23 May 2018). Ignition!: An Informal History of Liquid Rocket Propellants. Rutgers University Press. pp. 87–88. ISBN 978-0-8135-9918-2.
^ ^a ^b Smith D. F. (1963). "Chlorine Pentafluoride". Science. 141 (3585): 1039–1040. Bibcode:1963Sci...141.1039S. doi:10.1126/science.141.3585.1039. PMID 17739492. S2CID 39767609.
^ Šmalc A, Žemva B, Slivnik J, Lutar K (1981). "On the Synthesis of Chlorine Pentafluoride". Journal of Fluorine Chemistry. 17 (4): 381–383. doi:10.1016/S0022-1139(00)81783-2.
^ Greenwood, Norman N.; Earnshaw, Alan (1997). Chemistry of the Elements (2nd ed.). Butterworth-Heinemann. p. 834. ISBN 978-0-08-037941-8.