Iron(II) fluoride

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/h2*1H;/q;;+2/p-2 Y

Key: FZGIHSNZYGFUGM-UHFFFAOYSA-L Y

* InChI=1/2FH.Fe/h2*1H;/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 (Ksp)

| 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)  |

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

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]

## Contents

* 1 Structure and bonding
* 2 Selected physical properties
* 3 Synthesis and reactions
* 4 Uses
* 5 External links
* 6 References

## 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 Ksp = 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. ↑ 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.
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
4. ↑ 4.0 4.1 Sigma-Aldrich. "Material Safety Data Sheet". Sigma-Aldrich. http://www.sigmaaldrich.com/catalog/DisplayMSDSContent.do.
5. ↑ 5.0 5.1 Dale L. Perry (1995), "Handbook of Inorganic Compounds", page 167. CRC Press. ISBN:9780849386718
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.
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.
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.
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.
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.

* v
* t
* e

Iron compounds

Fe(-II)|

* Na2Fe(CO)4

Fe(0)|

* Fe(CO)5
* Fe2(CO)9
* Fe3(CO)12
* Fe(CO)3CH3COC2H2C6H6

Fe(I)|

* FeH

| Organoiron(I) compounds|

* (C5H5FeCO)2(CO)2

|

Fe(0,II)|

* Fe3C

Fe(II)|

* FeBr2
* FeCl2
* FeF2
* FeI2
* FeH2
* FeMoO4
* FeO
* Fe(OH)2
* FeS
* FeSO4
* FeSe
* FeSeO4
* FeSi2
* FeTiO3
* FeCO3
* FeC2O4
* Fe(C2H3O2)2
* Fe(C3H5O3)2
* FeC6H6O7
* FeC12H22O14
* Fe2CrO4
* Fe3(PO4)2
* H2Fe(CO)4
* Fe(HCO3)2
* Mg2FeH6

| Organoiron(II) compounds|

* Fe(C5H5)2
* Fe(C5H4P(C6H5)2)2
* C4H4Fe(CO)3
* C4H6Fe(CO)3

|

Fe(0,III)|

* Fe3P

Fe(II,III)|

* Fe3O4
* Fe3S4

Fe(III)|

* FeBr3
* FeCl3
* FeF3
* FeI3
* Fe(NO3)3
* Fe(acac)3
* FeOCl
* FeO(OH)
* FePO4
* Fe4(P2O7)3
* Fe2(CrO4)3
* Fe2(C2O4)3
* Fe2O3
* Fe2S3
* Fe2(SO4)3
* FeBO3
* FeB

| Organoiron(III) compounds|

* Fe(C5H5)2BF4
* C6H8O7⋅xFe3+⋅yNH3

|

Fe(VI)|

* K2FeO4
* BaFeO4

* v
* t
* e

Fluorine compounds

| HF |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | He

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LiF | BeF2 |  |  |  |  |  |  |  |  |  |  | BF3
B2F4 | CF4 | NF3 | OF2 | F− | Ne
NaF | MgF2 |  |  |  |  |  |  |  |  |  |  | AlF3 | SiF4 | PF3
PF5 | SF2
SF4
SF6 | ClF
ClF3
ClF5 | Ar
KF | CaF2 | ScF3 | TiF3
TiF4 | VF3
VF4
VF5 | CrF2
CrF3
CrF4
CrF5 | MnF2
MnF3 | FeF2
FeF3 | CoF2
CoF3 | NiF2 | CuF
CuF2 | ZnF2 | GaF3 | GeF4 | AsF3
AsF5 | SeF4
SeF6 | BrF3
BrF5 | KrF2
RbF | SrF2 | YF3 | ZrF4 | NbF4
NbF5 | MoF5
MoF6 | TcF6 | RuF3
RuF4
RuF5
RuF6 | RhF6 | PdF2 | AgF
AgF2
Ag2F | CdF2 | InF3 | SnF2
SnF4 | SbF3
SbF5 | TeF4 | IF
IF3
IF5
IF7 | XeF2
XeF4
XeF6
CsF | BaF2 | *  | HfF4 | TaF5 | WF4
WF6 | ReF4
ReF5
ReF6
ReF7 | OsF4
OsF5
OsF6 | IrF3
IrF5
IrF6 | PtF4
PtF6 | AuF3
Au2F10
AuF5·F2
| HgF2
Hg2F2 | TlF
TlF3 | PbF2
PbF4 | BiF3
BiF5 | Po | At | RnF2
Fr | Ra | **  | Rf | Db | Sg | Bh | Hs | Mt | Ds | Rg | Cn | Nh | Fl | Mc | Lv | Ts | Og
|  | ↓ |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
| * | LaF3 | CeF3 | Pr | NdF3 | PmF3 | SmF3
| Eu | Gd | Tb | DyF3 | Ho | Er | Tm | YbF3
| Lu |
| ** | AcF3 | ThF4 | Pa | UF3
UF4
UF5
UF6 | NpF3
NpF4
NpF5
NpF6
| PuF3
PuF4
PuF5
PuF6 | AmF3
AmF4 | CmF3 | Bk | Cf | Es | Fm | Md | No | Lr |

Other|

* AgBF4
* AgPF6
* Cs2AlF5
* K3AlF6
* Na3AlF6
* KAsF6
* LiAsF6
* NaAsF6
* HBF4
* KBF4
* LiBF4
* NaBF4
* RbBF4
* Ba(BF4)2
* Ni(BF4)2
* Pb(BF4)2
* Sn(BF4)2
* BaClF
* BaSiF6
* BaGeF6
* BrOF3
* BrO2F
* CBrF3
* CBr2F2
* CBr3F
* CClF3
* CCl2F2
* CCl3F
* CFN
* CF2O
* CF3I
* CHF3
* CH2F2
* CH3F
* C2Cl3F3
* C2H3F
* C6H5F
* C7H5F3
* C15F33N
* ClFO2
* CrFO4
* CrF2O2
* CsBF4
* NH4F
* FNO
* FNO2
* FNO3
* KHF2
* NaHF2
* ThOF2
* NH5F2
* (NH4)2SiF6
* F2OS
* F3OP
* PSF3
* HPF6
* HSbF6
* NH4PF6
* KPF6
* KSbF6
* LiPF6
* NaPF6
* NaSbF6
* Na2SiF6
* Na2TiF6
* Na2ZrF6
* TlPF6
* IOF3
* K2NbF7
* K2TaF7
* IO3F
* UO2F2

Chemical formulas

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