Hexamminecobalt(III) chloride
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Chloride.jpg) |
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| Names | |
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IUPAC name
Hexaamminecobalt(III) chloride
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| Other names
Cobalt hexammine chloride, hexaamminecobalt(III) chloride
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| Identifiers | |
| ECHA InfoCard | 100.030.991 |
| UNII | |
| Properties | |
| H18N6Cl3Co | |
| Molar mass | 267.48 g/mol |
| Appearance | yellow or orange crystals |
| Density | 1.71 g/cm3, |
| Melting point | decomposes |
| 0.26 M (20 °C) tribromide: 0.04 M (18 °C) |
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| Solubility | soluble in NH3 |
| Structure | |
| octahedral | |
| 0 D | |
| Hazards | |
| Main hazards | poison |
| R-phrases (outdated) | 36/37/38 |
| S-phrases (outdated) | none |
| Related compounds | |
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Other anions
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[Co(NH3)6]Br3 [Co(NH3)6](OAc)3 |
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Other cations
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[Cr(NH3)6]Cl3 [Ni(NH3)6]Cl2 |
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Related compounds
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[Co(H2NCH2CH2NH2)3]Cl3 [Co(NH3)5(H2O)]Cl3 |
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Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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 (what is   ?) |
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| Infobox references | |
[Co(NH3)5(H2O)]Cl3
[Co(NH3)5Cl]Cl2
Hexaamminecobalt(III) chloride is the chemical compound with the formula [Co(NH3)6]Cl3. This coordination compound is considered an archetypal "Werner complex", named after the pioneer of coordination chemistry, Alfred Werner. This salt consists of [Co(NH3)6]3+cations, each accompanied by three Cl− anions. The cation itself is a metal ammine complex with six ammonia molecules as ligands on the cobalt atom.
Originally this compound was described as the luteo (Latin: yellow) complex of cobalt, but this name has been discarded as modern chemistry considers color less important than molecular structure. Other similar complexes also had color names, such as purpureo (Latin: purple) for a pentammine complex, and praseo (Greek: green) and violeo (Latin: violet) for two isomeric tetrammine complexes.
[Co(NH3)6]3+ is diamagnetic, with a low-spin 3d6octahedral Co(III) center. The cation obeys the 18-electron rule and is considered to be a classic example of an exchange inert metal complex. As a manifestation of its inertness, [Co(NH3)6]Cl3 can be recrystallized unchanged from concentrated hydrochloric acid: the NH3 is so tightly bound to the Co(III) centers that it does not dissociate to allow its protonation. In contrast, labile metal ammine complexes, such as [Ni(NH3)6]Cl2, react rapidly with acids reflecting the lability of the Ni(II)–NH3 bonds. Upon heating, hexamminecobalt(III) begins to lose some of its ammine ligands, eventually producing a stronger oxidant.
The chloride ions in [Co(NH3)6]Cl3 can be exchanged with a variety of other anions such as nitrate, bromide, and iodide to afford the corresponding [Co(NH3)6]X3 derivative. Such salts are bright yellow and display varying degrees of water solubility.
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