Chlorine monofluoride

Names
IUPAC name Chlorine monofluoride
Other names Chlorine fluoride
Identifiers
CAS Number	7790-89-8 Y
3D model (JSmol)	Interactive image
ChemSpider	109879 N
ECHA InfoCard	100.029.300
PubChem CID	123266
UNII	UE4699O6C6 Y
CompTox Dashboard (EPA)	DTXSID50894057
InChI InChI=1S/FCl/c1-2 N Key: OMRRUNXAWXNVFW-UHFFFAOYSA-N N InChI=1/FCl/c1-2 Key: OMRRUNXAWXNVFW-UHFFFAOYAD
SMILES FCl
Properties
Chemical formula	ClF
Molar mass	54.45 g/mol
Density	1.62 g mL (liquid, −100 °C)
Melting point	−155.6 °C (−248.1 °F; 117.5 K)
Boiling point	−100.1 °C (−148.2 °F; 173.1 K)
Structure
Dipole moment	0.881 D (2.94 × 10−30 C m)
Thermochemistry
Heat capacity (C)	33.01 J K−1 mol−1
Std molar entropy (S⦵298)	217.91 J K−1 mol−1
Std enthalpy of formation (ΔfH⦵298)	−56.5 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

Chlorine monofluoride is a volatile interhalogen compound with the chemical formula ClF. It is a colourless gas at room temperature and is stable even at high temperatures. When cooled to −100 °C, ClF condenses as a pale yellow liquid. Many of its properties are intermediate between its parent halogens, Cl₂ and F₂.^[1]

Geometry

The molecular structure in the gas phase was determined by microwave spectroscopy; the bond length is r_e = 1.628341(4) Å.^[2]

The bond length in the crystalline ClF is 1.628(1) Å; the lengthening relative to the free molecule is due to an interaction of the type F-Br···ClMe with a distance of 2.640(1) Å. In its molecular packing it shows very short intermolecular Cl···Cl contacts of 3.070(1) Å between neighboring molecules.^[3]

Reactivity

Chlorine monofluoride is a versatile fluorinating agent, converting metals and non-metals to their fluorides and releasing Cl₂ in the process. For example, it converts tungsten to tungsten hexafluoride and selenium to selenium tetrafluoride:

W + 6 ClF → WF₆ + 3 Cl₂

Se + 4 ClF → SeF₄ + 2 Cl₂

FCl can also chlorofluorinate compounds, either by addition across a multiple bond or via oxidation. For example, it adds fluorine and chlorine to the carbon of carbon monoxide, yielding carbonyl chloride fluoride:

CO + ClF →