Iron(II) perchlorate is the inorganic compound with the formula . A green, water-soluble solid, it is produced by the reaction of iron metal with dilute perchloric acid followed by evaporation of the solution:[1]
Although the ferrous cation is a reductant and the perchlorate anion is a strong oxidant, in the absence of atmospheric oxygen, dissolved ferrous perchlorate is stable in aqueous solution because the electron transfer between both species is hindered by severe kinetic limitations. Being a weak Lewis base, the perchlorate anion is a poor ligand 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. The resulting high activation energy prohibits a thermodynamically spontaneous redox reaction (∆Gr < 0).
However, in aqueous solution, and under air, iron(II) perchlorate slowly oxidizes to iron(III) oxyhydroxide.[2]
The hexahydrate consists of discreet hexa-aquo-iron(II) divalent cations and perchlorate anions. It crystallizes with an orthorhombic structure. It has minor phase transitions at 245 and 336 K.[3]
In organic chemistry, iron(II) perchlorate can be used as a source of ferrous ions for the Fenton oxidation.