Iron(Ii) Fluoride

Iron(II) fluoride
Identifiers
CAS Number	7789-28-8 anhydrous ; 13940-89-1 (tetrahydrate) ;
3D model (JSmol)	Interactive image;
ChemSpider	74215 ;
PubChem CID	522690;
UNII	NP4W87HLVO ;
	InChI InChI=1S/2FH.Fe/h21H;/q;;+2/p-2 Key: FZGIHSNZYGFUGM-UHFFFAOYSA-L ; InChI=1/2FH.Fe/h21H;/q;;+2/p-2 Key: FZGIHSNZYGFUGM-NUQVWONBAX;
	SMILES [Fe+2].[F-].[F-];
Properties
Chemical formula	FeF2
Molar mass	93.84 g/mol (anhydrous) ; 165.902 g/mol (tetrahydrate)
Appearance	colorless transparent crystals
Density	4.09 g/cm3 (anhydrous) ; 2.20 g/cm3 (tetrahydrate)
Melting point	970 °C (1,780 °F; 1,240 K) (anhydrous) ; 100 °C (tetrahydrate)
Boiling point	1,100 °C (2,010 °F; 1,370 K) (anhydrous)
Solubility in water	165 g/100 mL
Solubility product (Ksp)	2.36×10−6
Solubility	insoluble in ethanol, ether; ; dissolves in HF
Magnetic susceptibility (χ)	+9500.0·10−6 cm3/mol
Structure
Crystal structure	Rutile (tetragonal), tP6
Space group	P42/mnm, No. 136
Hazards
Main hazards	Causes severe skin burns & eye damage; ; Hazardous decomposition products formed under fire conditions- Iron oxides
GHS pictograms
NFPA 704 (fire diamond)	0 4 2 COR
Flash point	not applicable
Related compounds
Other anions	Iron(II) chloride; Iron(II) bromide; Iron(II) iodide; Iron(II) oxide
Other cations	Manganese(II) fluoride; Cobalt(II) fluoride
Related compounds	Iron(III) fluoride
	Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
	verify (what is ?)
	Infobox references

Iron(II) fluoride or ferrous fluoride is an inorganic compound with the molecular formula FeF₂. It forms a tetrahydrate FeF₂·4H₂O that is often referred to by the same names. The anhydrous and hydrated forms are white crystalline solids.^[1]^[5]

Structure and bonding

Anhydrous FeF₂ adopts the TiO₂ rutile structure. As such, the iron cations are octahedral and fluoride anions are trigonal planar.^[6]^[7]

The tetrahydrate can exist in two structures, or polymorphs. One form is rhombohedral and the other is hexagonal, the former having a disorder.^[1]

Like most fluoride compounds, the anhydrous and hydrated forms of iron(II) fluoride feature high spin metal center. Low temperature neutron diffraction studies show that the FeF₂ is antiferromagnetic.^[8] Heat capacity measurements reveal an event at 78.3 K corresponding to ordering of antiferromagnetic state.^[9]

Selected physical properties

FeF₂ sublimes between 958 and 1178 K. Using Torsion and Knudsen methods, the heat of sublimation was experimentally determined and averaged to be 271 ± 2 kJ mole⁻¹.^[10]

The following reaction is proposed in order to calculate the atomization energy for Fe⁺:^[11]

FeF₂ + e → Fe⁺ + F₂ (or 2F) + 2e

Synthesis and reactions

The anhydrous salt can be prepared by reaction of ferrous chloride with anhydrous hydrogen fluoride.^[12] It is slightly soluble in water (with solubility product K_sp = 2.36×10⁻⁶ at 25 °C)^[13] as well as dilute hydrofluoric acid, giving a pale green solution.^[1] It is insoluble in organic solvents.^[5]

The tetrahydrate can be prepared by dissolving iron in warm hydrated hydrofluoric acid and precipitating the result by addition of ethanol.^[1] It oxidizes in moist air to give, inter alia, a hydrate of iron(III) fluoride, (FeF₃)₂·9H₂O.^[1]

Uses

FeF₂ is used to catalyze some organic reactions.^[14]

External links

National Pollutant Inventory - Fluoride and compounds fact sheet

References

↑ ^1.0 ^1.1 ^1.2 ^1.3 ^1.4 ^1.5 Penfold, B. R.; Taylor, M. R. (1960). "The crystal structure of a disordered form of iron(II) fluoride tetrahydrate". Acta Crystallographica 13 (11): 953–956. doi:10.1107/S0365110X60002302.
↑ John Rumble (June 18, 2018) (in English). CRC Handbook of Chemistry and Physics (99 ed.). CRC Press. pp. 5–188. ISBN 978-1138561632.
↑ Pradyot Patnaik. Handbook of Inorganic Chemicals. McGraw-Hill, 2002, ISBN:0-07-049439-8
↑ ^4.0 ^4.1 Sigma-Aldrich. "Material Safety Data Sheet". Sigma-Aldrich. http://www.sigmaaldrich.com/catalog/DisplayMSDSContent.do.
↑ ^5.0 ^5.1 Dale L. Perry (1995), "Handbook of Inorganic Compounds", page 167. CRC Press. ISBN:9780849386718
↑ Stout, J.; Stanley A. Reed (1954). "The Crystal Structure of MnF₂, FeF₂, CoF₂, NiF₂ and ZnF₂". J. Am. Chem. Soc. 76 (21): 5279–5281. doi:10.1021/ja01650a005.
↑ M.J.M., de Almeida; M.M.R., Costa; J.A., Paixão (1989-12-01). "Charge density of FeF2" (in en). Acta Crystallographica Section B 45 (6): 549–555. doi:10.1107/S0108768189007664. ISSN 0108-7681.
↑ Erickson, R. (June 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. Bibcode: 1953PhRv...90..779E.
↑ Stout, J.; Edward Catalano (December 1953). "Thermal Anomalies Associated with the Antiferromagnetic Ordering of FeF₂, CoF₃, and NiF₂". Physical Review 92 (6): 1575. doi:10.1103/PhysRev.92.1575. Bibcode: 1953PhRv...92.1575S.
↑ Bardi, Gianpiero; Brunetti, Bruno; Piacente, Vincenzo (1996-01-01). "Vapor Pressure and Standard Enthalpies of Sublimation of Iron Difluoride, Iron Dichloride, and Iron Dibromide". Journal of Chemical & Engineering Data 41 (1): 14–20. doi:10.1021/je950115w. ISSN 0021-9568.
↑ Kent, Richard; John L. Margrave (November 1965). "Mass Spectrometric Studies at High Temperatures. VIII. The Sublimation Pressure of Iron(II) Fluoride". Journal of the American Chemical Society 87 (21): 4754–4756. doi:10.1021/ja00949a016.
↑ W. Kwasnik "Iron(II) Fluoride" in Handbook of Preparative Inorganic Chemistry, 2nd Ed. Edited by G. Brauer, Academic Press, 1963, NY. Vol. 1. p. 266.
↑ "SOLUBILITY PRODUCT CONSTANTS". http://www4.ncsu.edu/~franzen/public_html/CH201/data/Solubility_Product_Constants.pdf.
↑ Wildermuth, Egon; Stark, Hans; Friedrich, Gabriele; Ebenhöch, Franz Ludwig; Kühborth, Brigitte; Silver, Jack; Rituper, Rafael (2000). "Ullmann's Encyclopedia of Industrial Chemistry". Ullmann's Encyclopedia of Industrial Chemistry. Weinheim: Wiley-VCH. doi:10.1002/14356007.a14_591.

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[pentay-1] 1.0 ^1.1 ^1.2 ^1.3 ^1.4 ^1.5 Penfold, B. R.; Taylor, M. R. (1960). "The crystal structure of a disordered form of iron(II) fluoride tetrahydrate". Acta Crystallographica 13 (11): 953–956. doi:10.1107/S0365110X60002302.

[crc-2] John Rumble (June 18, 2018) (in English). CRC Handbook of Chemistry and Physics (99 ed.). CRC Press. pp. 5–188. ISBN 978-1138561632.

[3] Pradyot Patnaik. Handbook of Inorganic Chemicals. McGraw-Hill, 2002, ISBN:0-07-049439-8

[SigmaMSDS-4] 4.0 ^4.1 Sigma-Aldrich. "Material Safety Data Sheet". Sigma-Aldrich. http://www.sigmaaldrich.com/catalog/DisplayMSDSContent.do.

[dale-5] 5.0 ^5.1 Dale L. Perry (1995), "Handbook of Inorganic Compounds", page 167. CRC Press. ISBN:9780849386718

[Stout_.26_Reed-6] Stout, J.; Stanley A. Reed (1954). "The Crystal Structure of MnF₂, FeF₂, CoF₂, NiF₂ and ZnF₂". J. Am. Chem. Soc. 76 (21): 5279–5281. doi:10.1021/ja01650a005.

[7] M.J.M., de Almeida; M.M.R., Costa; J.A., Paixão (1989-12-01). "Charge density of FeF2" (in en). Acta Crystallographica Section B 45 (6): 549–555. doi:10.1107/S0108768189007664. ISSN 0108-7681.

[Erickson-8] Erickson, R. (June 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. Bibcode: 1953PhRv...90..779E.

[Stout-9] Stout, J.; Edward Catalano (December 1953). "Thermal Anomalies Associated with the Antiferromagnetic Ordering of FeF₂, CoF₃, and NiF₂". Physical Review 92 (6): 1575. doi:10.1103/PhysRev.92.1575. Bibcode: 1953PhRv...92.1575S.

[10] Bardi, Gianpiero; Brunetti, Bruno; Piacente, Vincenzo (1996-01-01). "Vapor Pressure and Standard Enthalpies of Sublimation of Iron Difluoride, Iron Dichloride, and Iron Dibromide". Journal of Chemical & Engineering Data 41 (1): 14–20. doi:10.1021/je950115w. ISSN 0021-9568.

[Kent-11] Kent, Richard; John L. Margrave (November 1965). "Mass Spectrometric Studies at High Temperatures. VIII. The Sublimation Pressure of Iron(II) Fluoride". Journal of the American Chemical Society 87 (21): 4754–4756. doi:10.1021/ja00949a016.

[12] W. Kwasnik "Iron(II) Fluoride" in Handbook of Preparative Inorganic Chemistry, 2nd Ed. Edited by G. Brauer, Academic Press, 1963, NY. Vol. 1. p. 266.

[13] "SOLUBILITY PRODUCT CONSTANTS". http://www4.ncsu.edu/~franzen/public_html/CH201/data/Solubility_Product_Constants.pdf.

[Ullmann-14] Wildermuth, Egon; Stark, Hans; Friedrich, Gabriele; Ebenhöch, Franz Ludwig; Kühborth, Brigitte; Silver, Jack; Rituper, Rafael (2000). "Ullmann's Encyclopedia of Industrial Chemistry". Ullmann's Encyclopedia of Industrial Chemistry. Weinheim: Wiley-VCH. doi:10.1002/14356007.a14_591.

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Identifiers

CAS Number	7789-28-8 anhydrous^Y 13940-89-1 (tetrahydrate)^N
3D model (JSmol)	Interactive image
ChemSpider	74215^Y
PubChem CID	522690
UNII	NP4W87HLVO^Y
InChI InChI=1S/2FH.Fe/h21H;/q;;+2/p-2^Y Key: FZGIHSNZYGFUGM-UHFFFAOYSA-L^Y InChI=1/2FH.Fe/h21H;/q;;+2/p-2 Key: FZGIHSNZYGFUGM-NUQVWONBAX
SMILES [Fe+2].[F-].[F-]
Properties
Chemical formula	FeF₂
Molar mass	93.84 g/mol (anhydrous) 165.902 g/mol (tetrahydrate)
Appearance	colorless transparent crystals^[1]
Density	4.09 g/cm³ (anhydrous) 2.20 g/cm³ (tetrahydrate)
Melting point	970 °C (1,780 °F; 1,240 K) (anhydrous) 100 °C (tetrahydrate)^[3]
Boiling point	1,100 °C (2,010 °F; 1,370 K) (anhydrous)
Solubility in water	165 g/100 mL
Solubility product (K_sp)	2.36×10⁻⁶^[2]
Solubility	insoluble in ethanol, ether; dissolves in HF
Magnetic susceptibility (χ)	+9500.0·10⁻⁶ cm³/mol
Structure
Crystal structure	Rutile (tetragonal), tP6
Space group	P4₂/mnm, No. 136
Hazards
Main hazards	Causes severe skin burns & eye damage; Hazardous decomposition products formed under fire conditions- Iron oxides^[4]
GHS pictograms
NFPA 704 (fire diamond)	0 4 2 COR
Flash point	not applicable^[4]
Related compounds
Other anions	Iron(II) chloride Iron(II) bromide Iron(II) iodide Iron(II) oxide
Other cations	Manganese(II) fluoride Cobalt(II) fluoride
Related compounds	Iron(III) fluoride
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