Ferrous oxalate (iron(II) oxalate) refers to
inorganic compound
An inorganic compound is typically a chemical compound that lacks carbon–hydrogen bondsthat is, a compound that is not an organic compound. The study of inorganic compounds is a subfield of chemistry known as ''inorganic chemistry''.
Inorgan ...
s with the formula FeC
2O
4(H
2O)
x where x is 0 or 2. These are yellow compounds. Characteristic of
metal oxalate complexes, these compounds tend to be
polymeric, hence their low solubility in water.
Structure and reactions
Like other iron oxalates, ferrous oxalates feature octahedral Fe centers. The dihydrate FeC
2O
4(H
2O)
x is a
coordination polymer
Coordination may refer to:
* Coordination (linguistics), a compound grammatical construction
* Coordination complex, consisting of a central atom or ion and a surrounding array of bound molecules or ions
** A chemical reaction to form a coordinat ...
, consisting of chains of oxalate-bridged ferrous centers, each with two aquo ligands.
When heated to 120 °C, the dihydrate dehydrates, and the anhydrous ferrous oxalate decomposes near 190 °C. The products of thermal decomposition is a mixture of iron oxides and
pyrophoric
A substance is pyrophoric (from , , 'fire-bearing') if it ignites spontaneously in air at or below (for gases) or within 5 minutes after coming into contact with air (for liquids and solids). Examples are organolithium compounds and triethylb ...
iron metal, as well as released
carbon dioxide
Carbon dioxide is a chemical compound with the chemical formula . It is made up of molecules that each have one carbon atom covalent bond, covalently double bonded to two oxygen atoms. It is found in a gas state at room temperature and at norma ...
,
carbon monoxide
Carbon monoxide (chemical formula CO) is a poisonous, flammable gas that is colorless, odorless, tasteless, and slightly less dense than air. Carbon monoxide consists of one carbon atom and one oxygen atom connected by a triple bond. It is the si ...
, and water.
Ferrous oxalates are precursors to
iron phosphates, which are of value in batteries.
Natural occurrence
Anhydrous iron(II) oxalate is unknown among minerals as of 2020. However, the dihydrate is known as
humboldtine.
A related, although much more complex mineral is
stepanovite.
Na
g(H2O)6Fe(III)(C
2O
4)
3]·3H
2O is an unusual example of a naturally-occurring
ferrioxalate.
See also
*
Iron(III) oxalate
*
Potassium ferrioxalate
*
Sodium ferrioxalate
References
{{Oxalates
Iron(II) compounds
Oxalates
Inorganic compounds