Iron(II) perchlorate is the

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 ...

with the formula . A green, water-soluble solid, it is produced by the reaction of iron metal with dilute

perchloric acid Perchloric acid is a mineral acid with the formula H Cl O4. It is an oxoacid of chlorine. Usually found as an aqueous solution, this colorless compound is a stronger acid than sulfuric acid, nitric acid and hydrochloric acid. It is a powerful oxid ...

followed by evaporation of the solution: : Although the

ferrous In chemistry, iron(II) refers to the chemical element, element iron in its +2 oxidation number, oxidation state. The adjective ''ferrous'' or the prefix ''ferro-'' is often used to specify such compounds, as in ''ferrous chloride'' for iron(II ...

cation An ion () is an atom or molecule with a net electrical charge. The charge of an electron is considered to be negative by convention and this charge is equal and opposite to the charge of a proton, which is considered to be positive by convent ...

is a

reductant In chemistry, a reducing agent (also known as a reductant, reducer, or electron donor) is a chemical species that "donates" an electron to an (called the , , , or ). Examples of substances that are common reducing agents include hydrogen, carbon ...

and the

perchlorate A perchlorate is a chemical compound containing the perchlorate ion, , the conjugate base of perchloric acid (ionic perchlorate). As counterions, there can be metal cations, quaternary ammonium cations or other ions, for example, nitronium cat ...

anion An ion () is an atom or molecule with a net electrical charge. The charge of an electron is considered to be negative by convention and this charge is equal and opposite to the charge of a proton, which is considered to be positive by conven ...

is a strong

oxidant An oxidizing agent (also known as an oxidant, oxidizer, electron recipient, or electron acceptor) is a substance in a redox chemical reaction that gains or "Electron acceptor, accepts"/"receives" an electron from a (called the , , or ''electr ...

, in the absence of atmospheric oxygen, dissolved ferrous perchlorate is stable in

aqueous solution An aqueous solution is a solution in which the solvent is water. It is mostly shown in chemical equations by appending (aq) to the relevant chemical formula. For example, a solution of table salt, also known as sodium chloride (NaCl), in water ...

because the

electron transfer Electron transfer (ET) occurs when an electron relocates from an atom, ion, or molecule, to another such chemical entity. ET describes the mechanism by which electrons are transferred in redox reactions. Electrochemical processes are ET reactio ...

between both species is hindered by severe kinetic limitations. Being a weak

Lewis base A Lewis acid (named for the American physical chemist Gilbert N. Lewis) is a chemical species that contains an empty orbital which is capable of accepting an electron pair from a Lewis base to form a Lewis adduct. A Lewis base, then, is any sp ...

, the perchlorate anion is a poor

ligand In coordination chemistry, a ligand is an ion or molecule with a functional group that binds to a central metal atom to form a coordination complex. The bonding with the metal generally involves formal donation of one or more of the ligand's el ...

for the aqueous and does not contribute to the electron transfer by favoring the formation of an inner sphere complex giving rise to a possible reorganisation of the

activated complex In chemistry, an activated complex represents a collection of intermediate structures in a chemical reaction when bonds are breaking and forming. The activated complex is an arrangement of atoms in an arbitrary region near the saddle point ...

. The resulting high

activation energy In the Arrhenius model of reaction rates, activation energy is the minimum amount of energy that must be available to reactants for a chemical reaction to occur. The activation energy (''E''a) of a reaction is measured in kilojoules per mole (k ...

prohibits a thermodynamically spontaneous

redox reaction Redox ( , , reduction–oxidation or oxidation–reduction) is a type of chemical reaction in which the oxidation states of the reactants change. Oxidation is the loss of electrons or an increase in the oxidation state, while reduction is ...

(∆''G''_r < 0). However, in aqueous solution, and under air, iron(II) perchlorate slowly oxidizes to iron(III) oxyhydroxide. The hexahydrate consists of discrete hexa-aquo-iron(II) divalent cations and

anions. It crystallizes with an orthorhombic structure. It has minor phase transitions at 245 and 336 K.

Uses

In organic chemistry, iron(II) perchlorate can be used as a source of ferrous ions for the Fenton oxidation.

References

Iron(II) compounds Perchlorates {{inorganic-compound-stub