The Full Wiki


More info on Hexamminecobalt(III) chloride

Hexamminecobalt(III) chloride: Wikis


Note: Many of our articles have direct quotes from sources you can cite, within the Wikipedia article! This article doesn't yet, but we're working on it! See more info or our list of citable articles.



From Wikipedia, the free encyclopedia

Hexaamminecobalt(III) chloride
Hexamminecobalt(III) chloride
IUPAC name
Other names Cobalt hexammine chloride, hexaamminecobalt(III) chloride
CAS number 10534-89-1
Molecular formula H18N6Cl3Co
Molar mass 267.48 g/mol
Appearance yellow or orange crystals
Density 1.71 g/cm3,
Melting point


Solubility in water 0.26M (20 °C)
tribromide: 0.04M (18 °C)
Solubility in other solvents soluble in NH3
Dipole moment 0 D
R-phrases 36/37/38
S-phrases none
Related compounds
Other anions [Co(NH3)6]Br3
Other cations [Cr(NH3)6]Cl3
Related compounds [Co(H2NCH2CH2NH2)3]Cl 3


Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa)
Infobox references

Hexamminecobalt(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+ trications with three Cl anions. The term "ammine" refers to ammonia in its metal complexes, and the prefix hex (Greek: six) indicates that there are six ammonias per cation.

Originally this compound was described as a "luteo" (Latin: yellow) complex, 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. [1]

Properties and structure

[Co(NH3)6]3+ is diamagnetic, with a low-spin octahedral 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 chlorides 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.


Since CoCl3 is not available, [Co(NH3)6]Cl3 is prepared from cobalt(II) chloride. The latter is treated with ammonia and ammonium chloride followed by oxidation. Oxidants include hydrogen peroxide or oxygen in the presence of charcoal catalyst.[2] This salt appears to have been first reported by Fremy.[3]

The acetate salt can be prepared by aerobic oxidation of cobalt(II) acetate, ammonium acetate, and ammonia in methanol.[4] The acetate salt is highly water-soluble to the level of 1.9M (20 °C), vs. 0.26M for the trichloride.

[Co(NH3)6]3+ is a component of some protein crystallization methods to help solve their structures by X-ray crystallography.


  1. ^ Huheey James E., "Inorganic Chemistry" (3rd edition 1983), p.360
  2. ^ Bjerrum, J.; McReynolds, J. P. (1946). "Hexamminecobalt(III) Salts". Inorg. Synth. 2: 216–221. doi:10.1002/9780470132333.ch69.  
  3. ^ M. E. Fremy (1852). "Recherches sur le cobalt". Annales de chimie et de physique 35: 257–312.  
  4. ^ Lindholm, R. D.; Bause, Daniel E. (1978). "Hexamminecobalt(III) Salts". Inorg. Synth. 18: 67–69. doi:10.1002/9780470132494.ch14.  


Got something to say? Make a comment.
Your name
Your email address