Chlorine monofluoride
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| Names | |
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| IUPAC name
Chlorine monofluoride
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| Other names
Chlorine fluoride
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| Identifiers | |
3D model (
JSmol ) |
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| ChemSpider | |
ECHA InfoCard
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100.029.300 |
PubChem CID
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| UNII | |
CompTox Dashboard (EPA)
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| Properties | |
| 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 | |
| 0.881 D (2.94 × 10−30 C m) | |
| Thermochemistry | |
Heat capacity (C)
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33.01 J K−1 mol−1 |
Std molar
entropy (S⦵298) |
217.91 J K−1 mol−1 |
Std enthalpy of (ΔfH⦵298)formation |
−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).
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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 re = 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 →
