Iron(II) perchlorate

Iron(II) perchlorate
Names
IUPAC name
Iron(II) diperchlorate
Other names
  • Iron diperchlorate
  • Ferrous perchlorate
Identifiers
3D model (JSmol)
ChemSpider
ECHA InfoCard 100.034.263 Edit this at Wikidata
EC Number
  • 237-704-4
  • InChI=1S/2ClHO4.Fe.H2O/c2*2-1(3,4)5;;/h2*(H,2,3,4,5);;1H2/q;;+2;/p-2
    Key: BJDJGQJHHCBZJZ-UHFFFAOYSA-L
  • O.[O-]Cl(=O)(=O)=O.[O-]Cl(=O)(=O)=O.[Fe+2]
Properties
Fe(ClO4)2
Molar mass 254.75 g/mol
Appearance Green crystals
Density 2.15 g/cm3
Melting point 100 °C (212 °F; 373 K)
98 g/100 mL (25 °C)[1]
Structure[2]
Orthorhombic
Pmn21
a = 7.79 Å, b = 13.48 Å, c = 5.24 Å
Hazards
GHS labelling:
GHS03: OxidizingGHS07: Exclamation mark
Danger
H272, H315, H319, H335
P210, P220, P221, P261, P264, P271, P280, P302+P352, P304+P340, P305+P351+P338, P312, P321, P332+P313, P337+P313, P362, P370+P378, P403+P233, P405, P501
NFPA 704 (fire diamond)
Related compounds
Other cations
Manganese(II) perchlorate
Cobalt(II) perchlorate
Nickel(II) perchlorate
Related compounds
Iron(III) perchlorate
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).

Iron(II) perchlorate is the inorganic compound with the formula 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:[3]

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 Fe2+ and ClO4 is hindered by severe kinetic limitations. Being a weak Lewis base, the perchlorate anion is a poor ligand for the aqueous Fe2+ 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.[4]

The hexahydrate consists of discreet hexa-aquo-iron(II) divalent cations and perchlorate anions. It crystallizes with an orthorhombic structure.[2] It has minor phase transitions at 245 and 336 K.[5]

  1. ^ Mark W. Zettler; Daniela Sustac Roman (2014). "Iron(II) Perchlorate". Encyclopedia of Reagents for Organic Synthesis (EROS). doi:10.1002/047084289X.ri064.pub2.
  2. ^ a b Ghosh, Minakshi; Ray, Siddhartha (1981). "Twinning, disorder and phase transition in ferrous Perchlorate hexahydrate crystals". Zeitschrift für Kristallographie – Crystalline Materials. 155 (1–2): 129–137. Bibcode:1981ZK....155..129G. doi:10.1524/zkri.1981.155.1-2.129.
  3. ^ B.K. Chaudhuri (1975). "A new type of phase transition in M(ClO4)2(H2O)6 M = Fe, Co, Ni and Mn". Solid State Communications. 16 (6): 767–772. doi:10.1016/0038-1098(75)90071-X.
  4. ^ Philip George (1954). "The oxidation of ferrous perchlorate by molecular oxygen". Journal of the Chemical Society (Resumed): 4349–4359. doi:10.1039/JR9540004349.
  5. ^ D. P. Chiang; C. H. Peng; J. K. Mei; I. M. Jiang; S. C. Lin; Y. C. Chen; H. T. Liu; Y. F. Chen; W. S. Tse (2008). "Raman spectra of crystalline iron perchlorate hexahydrate". Journal of Raman Spectroscopy. 39 (3): 344–348. doi:10.1002/jrs.1801.