Copper(II) fluoride
Unit cell of the anhydrous form
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Ball-and-stick model of crystal packing in the anhydrous form
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Dihydrate
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| Names | |
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| IUPAC name
Copper difluoride
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| Other names
Cupric fluoride; Copper fluoride; Copper (2+) Difluoride
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| Identifiers | |
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3D model (JSmol)
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| ChemSpider | |
| ECHA InfoCard | 100.029.225 |
| EC Number |
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PubChem CID
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| UNII |
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CompTox Dashboard (EPA)
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| Properties | |
| CuF2 | |
| Molar mass | 101.543 g/mol (anhydrous) 137.573 g/mol (dihydrate) |
| Appearance | White crystalline powder When hydrated: Blue |
| Density | 4.23 g/cm3 (anhydrous) 2.934 g/cm3 (dihydrate)[1] |
| Melting point | 836 °C (1,537 °F; 1,109 K) (anhydrous) 130 °C (dihydrate, decomposes) |
| Boiling point | 1,676 °C (3,049 °F; 1,949 K) (anhydrous) |
| +1050.0·10−6 cm3/mol | |
| Thermochemistry | |
Std enthalpy of
formation (ΔfH⦵298) |
-63.8 kcal/mol (gas)[2] |
Enthalpy of fusion (ΔfH⦵fus)
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13 kcal/mol[2] |
Enthalpy of sublimation (ΔfHsublim)
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63.9 kcal/mol[3] |
| Hazards | |
| GHS labelling:[5] | |
| Danger | |
| H302, H314, H332 | |
| P260, P264, P270, P271, P280, P301+P330+P331, P303+P361+P353, P304+P340, P305+P351+P338, P310, P363, P405, P501 | |
| NIOSH (US health exposure limits): | |
PEL (Permissible)
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TWA 1 mg/m3 (as Cu)[4] |
REL (Recommended)
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TWA 1 mg/m3 (as Cu)[4] |
IDLH (Immediate danger)
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TWA 100 mg/m3 (as Cu)[4] |
| Related compounds | |
Other anions
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Copper(II) bromide Copper(II) chloride |
Other cations
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Silver(II) fluoride Cobalt(II) fluoride |
Related compounds
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Copper(I) fluoride |
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Infobox references
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Copper(II) fluoride or cupric fluoride is an inorganic compound with the chemical formula CuF2. The anhydrous form is a white, ionic, crystalline, hygroscopic salt with a distorted rutile-type crystal structure, similar to other fluorides of chemical formulae MF2 (where M is a metal). The dihydrate, CuF2·2H2O, is blue in colour.[6]
Properties
Copper(II) fluoride is slightly soluble in water, but starts to decompose in hot water, producing basic F− and Cu(OH)+ ions.
Structure
Copper(II) fluoride has a monoclinic crystal structure[7] and cannot achieve a higher-symmetry structure. It forms rectangular prisms with a parallelogram base.[8] Each copper ion has four neighbouring fluoride ions at 1.93 Å separation and two further away at 2.27 Å.[6] This distorted octahedral [4+2] coordination is a consequence of the Jahn–Teller effect in d9 copper(II),[9] and leads to a distorted rutile structure similar to that of chromium(II) fluoride, CrF2, which is a d4 compound.[6]
| Copper coordination | Fluorine coordination |
|---|---|
Synthesis
Copper(II) fluoride can be synthesized from copper and fluorine at elevated temperatures. At 500 °C (932 °F) a 53% conversion is achieved.[10]
- Cu + F2 → CuF2
Uses
Cupric fluoride catalyzes the decomposition of nitric oxides in emission control systems.[11]
Copper(II) fluoride can be used to make fluorinated aromatic hydrocarbons by reacting with aromatic hydrocarbons in an oxygen-containing atmosphere at temperatures above 450 °C (842 °F). This reaction is simpler than the Sandmeyer reaction, but is only effective in making compounds that can survive at the temperature used. A coupled reaction using oxygen and 2 HF regenerates the copper(II) fluoride, producing water.[12] This method has been proposed as a "greener" method of producing fluoroaromatics since it avoids producing toxic waste products such as ammonium fluoride.
Reactions
It loses fluorine in the molten stage at temperatures above 950 °C (1742 °F).
- 2 CuF2 → 2 CuF + F2
- 2 CuF → CuF2 + Cu
The complex anions CuF3−, CuF42− and CuF64− are formed if CuF2 is exposed to substances containing fluoride ions F−.
References
- ^ Pradyot Patnaik. Handbook of Inorganic Chemicals. McGraw-Hill, 2002, ISBN 0-07-049439-8
- ^ a b T. C. Ehlert; J. S. Wang (1977). "Thermochemistry of the copper fluorides". Journal of Physical Chemistry. 81 (22): 2069–2073. doi:10.1021/j100537a005.
- ^ Kent, R. A.; Mcdonald, J. D.; Margrave, J. L. (1966). "Mass Spectrometric Studies at High Temperatures. IX. The Sublimation Pressure of Copper(II) Fluoride". Journal of Physical Chemistry. 70 (3): 874–877. doi:10.1021/j100875a042.
- ^ a b c NIOSH Pocket Guide to Chemical Hazards. "#0150". National Institute for Occupational Safety and Health (NIOSH).
- ^ "Copper Fluoride - ESPI Metals". www.espimetals.com. Retrieved 2026-02-19.
- ^ a b c d Greenwood, Norman N.; Earnshaw, Alan (1997). Chemistry of the Elements (2nd ed.). Butterworth-Heinemann. pp. 1184–1185. doi:10.1016/C2009-0-30414-6. ISBN 978-0-08-037941-8.
- ^ a b Fischer, P.; Hälg, W.; Schwarzenbach, D.; Gamsjäger, H. (1974). "Magnetic and crystal structure of copper(II) fluoride". J. Phys. Chem. Solids. 35 (12): 1683–1689. doi:10.1016/S0022-3697(74)80182-4.
- ^ C. Billy; H. M. Haendler (1957). "The Crystal Structure of Copper(II) Fluoride". Journal of the American Chemical Society. 79 (5): 1049–51. doi:10.1021/ja01562a011.
- ^ Greenwood, Norman N.; Earnshaw, Alan (1997). Chemistry of the Elements (2nd ed.). Butterworth-Heinemann. pp. 1190–1191. doi:10.1016/C2009-0-30414-6. ISBN 978-0-08-037941-8.
- ^ H. M. Haendler; L. H. Towle; E. F. Bennett; W. L. Patterson (1954). "The Reaction of Fluorine with Copper and Some of its Compounds. Some Properties of Copper(II) Fluoride". Journal of the American Chemical Society. 76 (8): 2178–2179. doi:10.1021/ja01637a039.
- ^ Meshri, Dayal T. (2000), "Fluorine compounds, inorganic, copper", Kirk-Othmer Encyclopedia of Chemical Technology, New York: John Wiley, doi:10.1002/0471238961.0315161613051908.a01, ISBN 9780471238966
- ^ M. A. Subramanian; L. E. Manzer (2002). "A "Greener" Synthetic Route for Fluoroaromatics via Copper (II) Fluoride". Science. 297 (5587): 1665. doi:10.1126/science.1076397. PMID 12215637. S2CID 32697750.
Further reading
- Shashkin, S. Y.; Goddard III, W. A. (1986). "Electron Correlation effects in ligand field parameters and other properties of copper II fluoride". Journal of Physical Chemistry. 90 (2): 250–255. doi:10.1021/j100274a010.
- P. C. de Mello; M. Hehenberg; S. Larson; M. Zerner (1980). "Studies of the electronic structure of copper fluorides and copper chlorides". Journal of the American Chemical Society. 102 (4): 1278–1288. doi:10.1021/ja00524a010.