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Iron(II) fluoride
Encyclopedia
Iron fluoride (also ferrous fluoride) is a chemical compound
with formula FeF2. It is a green crystalline solid that melts at about 1000°C. It is used in ceramics and as a catalyst in some organic reactions.
The anhydrous salt can be prepared by reacting the elements. It has the TiO2 rutile
structure where the iron atoms are octahedrally coordinated and the fluoride ions three coordinate.
studies at low temperatures, Iron(II) fluoride is antiferromagnetic. 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.
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.
The following reaction was propsed in order to calculate the atomization energy for Fe+:
, FeF2·4H2O, (CAS Number 13940-89-1). The latter exists in two crystal structures, one rhombohedral and one hexagonal, the former having a disordered The tetrahydrate oxidizes in moist air to a hydrate of iron(III) fluoride
, 2FeF3·9H2O.
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.
Though calculations using the lattice constants, found through X-ray crystallography
, the bond lengths were determined as follows:
Chemical compound
A chemical compound is a pure chemical substance consisting of two or more different chemical elements that can be separated into simpler substances by chemical reactions. Chemical compounds have a unique and defined chemical structure; they consist of a fixed ratio of atoms that are held together...
with formula FeF2. It is a green crystalline solid that melts at about 1000°C. It is used in ceramics and as a catalyst in some organic reactions.
The anhydrous salt can be prepared by reacting the elements. It has the TiO2 rutile
Titanium dioxide
Titanium dioxide, also known as titanium oxide or titania, is the naturally occurring oxide of titanium, chemical formula . When used as a pigment, it is called titanium white, Pigment White 6, or CI 77891. Generally it comes in two different forms, rutile and anatase. It has a wide range of...
structure where the iron atoms are octahedrally coordinated and the fluoride ions three coordinate.
Physical Properties
Through neutron diffractionNeutron diffraction
Neutron diffraction or elastic neutron scattering is the application of neutron scattering to the determination of the atomic and/or magnetic structure of a material: A sample to be examined is placed in a beam of thermal or cold neutrons to obtain a diffraction pattern that provides information of...
studies at low temperatures, Iron(II) fluoride is antiferromagnetic. Heat capacity
Heat capacity
Heat capacity , or thermal capacity, is the measurable physical quantity that characterizes the amount of heat required to change a substance's temperature by a given amount...
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.
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.
The following reaction was propsed in order to calculate the atomization energy for Fe+:
- FeF2 + e → Fe+ +F2(or 2F) + 2e
Crystal Structure
It is slightly soluble in water (Ksp = 2.36 × 10−6) and can be crystallized from it as a colorless tetrahydrateHydrate
Hydrate is a term used in inorganic chemistry and organic chemistry to indicate that a substance contains water. The chemical state of the water varies widely between hydrates, some of which were so labeled before their chemical structure was understood....
, FeF2·4H2O, (CAS Number 13940-89-1). The latter exists in two crystal structures, one rhombohedral and one hexagonal, the former having a disordered The tetrahydrate oxidizes in moist air to a hydrate of iron(III) fluoride
Iron(III) fluoride
Iron fluoride, also known as ferric fluoride, is an inorganic compound. It exists in an anhydrous form as well as two hydrated forms . It is produced commercially mostly for laboratory work and is not as useful as the related compound iron chloride...
, 2FeF3·9H2O.
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.
Though calculations using the lattice constants, found through X-ray crystallography
X-ray crystallography
X-ray crystallography is a method of determining the arrangement of atoms within a crystal, in which a beam of X-rays strikes a crystal and causes the beam of light to spread into many specific directions. From the angles and intensities of these diffracted beams, a crystallographer can produce a...
, the bond lengths 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