Iron(II) perchlorate

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| Reference =

| Name = Iron(II) perchlorate

| IUPACName = Iron(II) diperchlorate

| PIN =

| SystematicName =

| OtherNames = {{Unbulleted list

| Iron diperchlorate

| Ferrous perchlorate

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| ImageFile = Ferrous aq6 perchlorate.svg

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| Section1 = {{Chembox Identifiers

| Abbreviations =

| index1_label = hydrate

| CASNo1 = 335159-18-7

| CASNo_Ref = {{Cascite|changed|??}}

| ChEBI =

| ChemSpiderID = 146076

| EC_number = 237-704-4

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| KEGG =

| PubChem = 71311361

| RTECS =

| SMILES = O.[O-]Cl(=O)(=O)=O.[O-]Cl(=O)(=O)=O.[Fe+2]

| StdInChI=1S/2ClHO4.Fe.H2O/c2*2-1(3,4)5;;/h2*(H,2,3,4,5);;1H2/q;;+2;/p-2

| StdInChIKey = BJDJGQJHHCBZJZ-UHFFFAOYSA-L

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| Section2 = {{Chembox Properties

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| Appearance = Green crystals

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| Density = 2.15 g/cm³

| Formula = Fe(ClO₄)₂

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| MolarMass = 254.75 g/mol

| MeltingPt =

| MeltingPtC = 100

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| Solubility = 98 g/100 mL (25 °C){{cite journal |author1=Mark W. Zettler |author2=Daniela Sustac Roman |title=Iron(II) Perchlorate |journal=Encyclopedia of Reagents for Organic Synthesis |date=2014 |doi=10.1002/047084289X.ri064.pub2 |language=en}}

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| Section3 = {{Chembox Structure

| Structure_ref = {{cite journal |doi=10.1524/zkri.1981.155.1-2.129 |language=en |title=Twinning, disorder and phase transition in ferrous Perchlorate hexahydrate crystals |journal=Zeitschrift für Kristallographie – Crystalline Materials |date=1981 |volume=155 |issue=1–2 |pages=129–137 |bibcode=1981ZK....155..129G |last1=Ghosh |first1=Minakshi |last2=Ray |first2=Siddhartha }}

| CrystalStruct = Orthorhombic

| SpaceGroup = Pmn2₁

| PointGroup =

| LattConst_a = 7.79 Å

| LattConst_b = 13.48 Å

| LattConst_c = 5.24 Å

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| Section4 = {{Chembox Thermochemistry

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| Section5 = {{Chembox Explosive

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| Section7 = {{Chembox Hazards

| AutoignitionPt =

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| MainHazards =

| NFPA-H = 2

| NFPA-F = 0

| NFPA-I = 1

| NFPA-S = OX

| PEL =

| REL =

| ExternalSDS =

| GHSPictograms = {{GHS03}}{{GHS07}}

| GHSSignalWord = Danger

| HPhrases = {{h-phrases|272|315|319|335}}

| PPhrases = {{p-phrases|210|220|221|261|264|271|280|302+352|304+340|305+351+338|312|321|332+313|337+313|362|370+378|403+233|405|501}}

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| Section9 = {{Chembox Related

| OtherAnions =

| OtherCations = Manganese(II) perchlorate
Cobalt(II) perchlorate
Nickel(II) perchlorate

| OtherFunction =

| OtherFunction_label =

| OtherCompounds = Iron(III) perchlorate

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Iron(II) perchlorate is the inorganic compound with the formula {{chem2|Fe(ClO4)2*6H2O}}. A green, water-soluble solid, it is produced by the reaction of iron metal with dilute perchloric acid followed by evaporation of the solution:{{cite journal |author1=B.K. Chaudhuri |title=A new type of phase transition in M(ClO₄)₂(H₂O)₆ M = Fe, Co, Ni and Mn |journal=Solid State Communications |date=1975 |volume=16 |issue=6 |pages=767-772 |doi=10.1016/0038-1098(75)90071-X |language=en}}

: {{chem2|Fe + 2 HClO4 + 6 H2O -> Fe(ClO4)2*6H2O + H2}}

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 {{chem2|Fe(2+) and ClO4-}} is hindered by severe kinetic limitations. Being a weak Lewis base, the perchlorate anion is a poor ligand for the aqueous {{chem2|Fe(2+)}} 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 (∆G_r < 0).

However, in aqueous solution, and under air, iron(II) perchlorate slowly oxidizes to iron(III) oxyhydroxide.{{cite journal |author1=Philip George |title=The oxidation of ferrous perchlorate by molecular oxygen |journal=Journal of the Chemical Society (Resumed) |date=1954 |pages=4349-4359 |doi=10.1039/JR9540004349 |language=en}}

The hexahydrate consists of discrete 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.{{cite journal |author1=D. P. Chiang |author2=C. H. Peng |author3=J. K. Mei |author4=I. M. Jiang |author5=S. C. Lin |author6=Y. C. Chen |author7=H. T. Liu |author8=Y. F. Chen |author9=W. S. Tse |title=Raman spectra of crystalline iron perchlorate hexahydrate |journal=Journal of Raman Spectroscopy |date=2008 |volume=39 |issue=3 |pages=344-348 |doi=10.1002/jrs.1801 |language=en}}