Iron(II) fluoride
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3D model (JSmol)
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| ChemSpider | |
| ECHA InfoCard | 100.029.232 |
PubChem CID
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CompTox Dashboard (EPA)
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| Properties | |
| FeF2 | |
| Molar mass | 93.84 g/mol (anhydrous) 165.90 g/mol (tetrahydrate) |
| Appearance | white crystalline solid |
| Density | 4.09 g/cm3 (anhydrous) 2.20 g/cm3 (tetrahydrate) |
| Melting point | 970 °C (anhydrous) 100 °C (tetrahydrate) [1] |
| Boiling point | 1100 °C (anhydrous) |
| insoluble in ethanol, ether; dissolves in HF | |
| Structure | |
| Rutile (tetragonal), tP6 | |
| P42/mnm, No. 136 | |
| Hazards | |
| Occupational safety and health (OHS/OSH): | |
Main hazards
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Causes severe skin burns & eye damage; Hazardous decomposition products formed under fire conditions- Iron oxides [2] |
| Flash point | not applicable [2] |
| Related compounds | |
Other anions
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iron(II) oxide, iron(II) chloride |
Other cations
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manganese(II) fluoride, cobalt(II) fluoride |
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Iron(II) fluoride (also ferrous fluoride) is a chemical compound with formula FeF2. It is a green crystalline solid that melts at about 1000°C.[3] It is used in ceramics and as a catalyst in some organic reactions.[3]
The anhydrous salt can be prepared by reacting the elements.[4] It has the TiO2 rutile structure where the iron atoms are octahedrally coordinated and the fluoride ions three coordinate.[4]
Physical Properties
Through neutron diffraction studies at low temperatures, Iron(II) fluoride is antiferromagnetic.[5] Heat capacity was measured over a temperature range 12-300°K. At temperature 78.3°K a thermal anomalie occurred. This thermal anomalie can be explained as Iron(II) fluoride passing from its disordered paramagnetic state to a more ordered antiferromagnetic state.[6]
The vapor species were identified between 965 and 1149°K. Using mass spectrometry the heat of sublimation was experimentally determined and averaged to be 75.56 ± 0.23kcal. mole−1.[7] The following reaction was propsed in order to calculate the atomization energy for Fe+:
- FeF2 + e → Fe+ +F2(or 2F) + 2e [7]
Crystal Structure
It is slightly soluble in water[4] (Ksp = 2.36 × 10−6)[8] and can be crystallized from it as a colorless tetrahydrate, FeF2·4H2O, (CAS Number 13940-89-1). The latter exists in two crystal structures, one rhombohedral and one hexagonal, the former having a disordered [9] The tetrahydrate oxidizes in moist air to a hydrate of iron(III) fluoride, 2FeF3·9H2O.[9]
To determine impurities in previous crystal structuring of the FeF2 the compound was first melted and then through spectrochemical analysis the percent of impurities could be determined.[10]
Though calculations using the lattice constants, found through X-ray crystallography, the bond lengths[10] were determined as follows:
- d1(Fe-F): 2.03± 0.07Å
- d2(Fe-F): 2.10± 0.04Å
- d (F-F): 2.59± 0.13Å
External links
References
- ^ Pradyot Patnaik. Handbook of Inorganic Chemicals. McGraw-Hill, 2002, ISBN 0070494398
- ^ a b Sigma-Aldrich. "Material Safety Data Sheet". Sigma-Aldrich. Retrieved 5 April 2011.
- ^ a b Iron (II) Fluoride in the Chembok site. Accessed on 2011-01-16.
- ^ a b c Greenwood, Norman N.; Earnshaw, Alan (1997). Chemistry of the Elements (2nd ed.). Butterworth-Heinemann. ISBN 978-0-08-037941-8.
- ^ Erickson, R (1953). "Neutron Diffraction Studies of Antiferromagnetism in Manganous Fluoride and Some Isomorphous Compounds". Physical Review. 90 (5): 779–785. doi:10.1103/PhysRev.90.779.
{{cite journal}}: Unknown parameter|month=ignored (help) - ^ Stout, J (1953). "Thermal Anomalies Associated with the Antiferromagnetic Ordering of FeF2, CoF3, and NiF2". Physical Review. 92 (6): 1575–1575. doi:10.1103/PhysRev.92.1575.
{{cite journal}}: Unknown parameter|coauthors=ignored (|author=suggested) (help); Unknown parameter|month=ignored (help) - ^ a b Kent, Richard (1965). "Mass Spectometric at High Temperatures. VIII. The Sublimation Pressure of Iron(II) Fluoride". Journal of the American Chemical Society. 87 (21): 4754–4756.
{{cite journal}}: Unknown parameter|coauthors=ignored (|author=suggested) (help); Unknown parameter|month=ignored (help) - ^ Ksp solubility constant for common salts. Solubility of things site. Accessed on 2011-01-16.
- ^ a b Penfold, B. R.; Taylor, M. R. (1960). "The crystal structure of a disordered form of iron(II) fluoride tetrahydrate". Acta Crystallographica. 13: 953–956. doi:10.1107/S0365110X60002302.
- ^ a b Stout, J. (Nov. 5, 1954). "The Crystal Structure of MnF2, FeF2, CoF2, NiF2 and ZnF2". Crystal Structures of Anhydrous Fluorides: 5279–5281.
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