Cobalt(II) perchlorate is an inorganic chemical compound with the formula Co(ClO₄)₂·''n''H₂O (''n'' = 0,6). The pink anhydrous and red hexahydrate forms are both

hygroscopic Hygroscopy is the phenomenon of attracting and holding water molecules via either absorption (chemistry), absorption or adsorption from the surrounding Natural environment, environment, which is usually at normal or room temperature. If water mol ...

solids.

Preparation and reactions

Cobalt(II) perchlorate hexahydrate is produced by reacting

cobalt Cobalt is a chemical element; it has Symbol (chemistry), symbol Co and atomic number 27. As with nickel, cobalt is found in the Earth's crust only in a chemically combined form, save for small deposits found in alloys of natural meteoric iron. ...

metal or cobalt(II) carbonate with

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 the evaporation of the solution: :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 Cobalt is a chemical element; it has symbol Co and atomic number 27. As with nickel, cobalt is found in the Earth's crust only in a chemically combined form, save for small deposits found in alloys of natural meteoric iron. The free element, ...

at 170 °C. Instead, anhydrous cobalt(II) perchlorate is produced from the reaction of

dichlorine hexoxide Dichlorine hexoxide is the chemical compound with the molecular formula or , which is correct for its gaseous state. However, in liquid or solid form, this chlorine oxide ionizes into the dark red ionic compound chloryl perchlorate or dioxochlor ...

and

cobalt(II) chloride Cobalt(II) chloride is an inorganic compound, a salt of cobalt and chlorine, with the formula . The compound forms several hydrates ·''n'', for ''n'' = 1, 2, 6, and 9. Claims of the formation of tri- and tetrahydrates have not been confirmed.M. ...

, followed by heating in a vacuum at 75 °C.

Structure

The anhydrous form consists of octahedral Co(ClO₄)₆ centers, with tridentate perchlorate ligands. On the other hand, the

orthorhombic In crystallography, the orthorhombic crystal system is one of the 7 crystal systems. Orthorhombic Lattice (group), lattices result from stretching a cubic crystal system, cubic lattice along two of its orthogonal pairs by two different factors, res ...

hexahydrate consists of isolated o(H₂O)₆sup>2+ octahedrons and

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 ...

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.

References

{{Perchlorates Cobalt(II) compounds Perchlorates