Cobalt(II) perchlorate

Cobalt(II) perchlorate is an inorganic chemical compound with the formula Co(ClO₄)₂·nH₂O (n = 0,6). The pink anhydrous and red hexahydrate forms are both hygroscopic solids.

Cobalt(II) perchlorate

Hexahydrate
Names
Systematic IUPAC name Cobalt(II) diperchlorate
Other names Cobaltous perchlorate Cobalt diperchlorate
Identifiers
CAS Number	13455-31-7
3D model (JSmol)	Interactive image hexahydrate: Interactive image
ChemSpider	24278
ECHA InfoCard	100.033.307
EC Number	236-653-5
PubChem CID	26064
CompTox Dashboard (EPA)	DTXSID2094003
InChI InChI=1S/2ClHO4.Co/c2*2-1(3,4)5;/h2*(H,2,3,4,5);/q;;+2/p-2 Key: BSUSEPIPTZNHMN-UHFFFAOYSA-L hexahydrate: InChI=1S/2ClHO4.Co.6H2O/c2*2-1(3,4)5;;;;;;;/h2*(H,2,3,4,5);;6*1H2/q;;+2;;;;;;/p-2 Key: KPOBHNYTWJSVKF-UHFFFAOYSA-
SMILES [O-]Cl(=O)(=O)=O.[O-]Cl(=O)(=O)=O.[Co+2] hexahydrate: [O-]Cl(=O)(=O)=O.[O-]Cl(=O)(=O)=O.[Co+2].O.O.O.O.O.O
Properties
Chemical formula	Co(ClO4)2
Molar mass	257.83 g/mol
Appearance	Pink solid (anhydrous) Dark-red crystals (hexahydrate)
Density	3.33 g/cm3
Melting point	170 °C (338 °F; 443 K)[1] (decomposition, hexahydrate)
Solubility in water	113 g/100 mL (25 °C)
Solubility	Insoluble in ethanol and acetone
Hazards
GHS labelling:
Pictograms
Signal word	Danger
NFPA 704 (fire diamond)	2 0 1 OX
Safety data sheet (SDS)	Fisher SDS
Related compounds
Other cations	Iron(II) perchlorate Nickel(II) perchlorate
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). Infobox references

Preparation and reactions

Cobalt(II) perchlorate hexahydrate is produced by reacting cobalt metal or cobalt(II) carbonate with perchloric acid, followed by the evaporation of the solution:^[1]

CoCO₃ + 2 HClO₄ → Co(ClO₄)₂ + H₂O + CO₂

The anhydrous form cannot be produced from the hexahydrate by heating, as it instead decomposes to cobalt(II,III) oxide at 170 °C. Instead, anhydrous cobalt(II) perchlorate is produced from the reaction of dichlorine hexoxide and cobalt(II) chloride, followed by heating in a vacuum at 75 °C.^[1][2]

Structure

The anhydrous form consists of octahedral Co(ClO₄)₆ centers, with tridentate perchlorate ligands.^[3] On the other hand, the orthorhombic hexahydrate consists of isolated [Co(H₂O)₆]²⁺ octahedrons and perchlorate anions with lattice constants a = 7.76 Å, b = 13.44 Å and c = 5.20 Å. The hexahydrate undergoes phase transitions at low temperatures.^[4][5]