Hexamminecobalt(III) chloride

Hexamminecobalt(III) chloride is an inorganic compound with the chemical formula Co(NH3)6Cl3. This compound is a common example of a coordination complex in which a central cobalt atom is surrounded by six ammonia (NH3) ligands. It is a chloride salt of the hexaamminecobalt(III) cation. The compound is of interest both in the field of inorganic chemistry and for its applications in various chemical processes.

Structure and Properties

Hexamminecobalt(III) chloride crystallizes in an octahedral geometry, which is typical for complexes with six ligands. The cobalt atom is at the center of the octahedron, with the six ammonia molecules acting as ligands bound to the cobalt through their nitrogen atoms. The compound is an ionic solid, consisting of [Co(NH3)6]3+ cations and Cl- anions.

The compound is highly soluble in water, forming a purple solution. This solubility is attributed to the ionic nature of the compound and the strong interaction between the cations, anions, and water molecules. The purple color is characteristic of the cobalt(III) ion in a complex, indicating the presence of d-d transitions as a result of the ligand field.

Synthesis

Hexamminecobalt(III) chloride is typically synthesized by the reaction of cobalt(II) chloride (CoCl2) with ammonia in the presence of an oxidizing agent. The oxidation of cobalt(II) to cobalt(III) is necessary for the formation of the complex. A common oxidizing agent used in this synthesis is hydrogen peroxide (H2O2). The overall reaction can be represented as follows:

CoCl2 + 6NH3 + H2O2 + 5HCl → [Co(NH3)6]Cl3 + 2H2O

The reaction involves the initial formation of a cobalt(II) ammonia complex, which is then oxidized to the cobalt(III) state. The final product is precipitated by the addition of excess hydrochloric acid (HCl).

Applications

Hexamminecobalt(III) chloride has been studied for its potential applications in various fields. One area of interest is its use as a catalyst in organic synthesis, particularly in reactions that involve the reduction or hydrolysis of organic compounds. Additionally, the compound has been explored for its antimicrobial properties, offering potential applications in the development of antimicrobial agents.

Safety and Handling

As with many cobalt compounds, hexamminecobalt(III) chloride should be handled with care. Cobalt compounds can be toxic if ingested or inhaled, and they may cause allergic skin reactions. Proper personal protective equipment, such as gloves and safety glasses, should be worn when handling this compound. Additionally, it should be used in a well-ventilated area to minimize exposure to dust or vapors.

See Also

• Coordination chemistry
• Ligand field theory
• Inorganic synthesis