Sodium tris(carbonato)cobalt(III) is the name given to the
inorganic compound
In chemistry, an inorganic compound is typically a chemical compound that lacks carbon–hydrogen bonds, that is, a compound that is not an organic compound. The study of inorganic compounds is a subfield of chemistry known as '' inorganic chemist ...
with the formula Na
3Co(CO
3)
3•3H
2O. The salt contains an olive-green metastable cobalt(III)
coordination complex
A coordination complex consists of a central atom or ion, which is usually metallic and is called the ''coordination centre'', and a surrounding array of bound molecules or ions, that are in turn known as ''ligands'' or complexing agents. Many ...
. The salt is sometimes referred to as the “Field-Durrant precursor” and is prepared by the “Field-Durrant synthesis”. It is used in the synthesis of other cobalt(III) complexes. Otherwise cobalt(III) complexes are generated from cobalt(II) precursors, a process that requires an oxidant.
Synthesis
An aqueous solution of cobalt(II) nitrate and hydrogen peroxide is added to a solution of sodium bicarbonate, leading to precipitation of the olive solid. The method is a modification of the synthesis of what has been described as “Co
2(CO
3)
3”.
Structure and synthetic applications
The identity of this complex anion is uncertain, suggestions include
o(κ2-CO3)3sup>3-,
o(κ1-CO3H)3(OH)3sup>3-, and
o(κ2-CO3)2(κ1-CO3)(OH2)sup>3-. Thermal gravimetric analysis favors the presence of one aquo ligand, and
infra-red spectroscopy
Infrared spectroscopy (IR spectroscopy or vibrational spectroscopy) is the measurement of the interaction of infrared radiation with matter by absorption, emission, or reflection. It is used to study and identify chemical substances or function ...
indicates the presence of both bi- and unidentate carbonate ligands. The addition of
o(NH3)6l
3 to fresh solutions of sodium tris(carbonato)cobalt(III) precipitates anhydrous salt
o(NH3)6Co(κ
2-CO
3)
3]. This salt has been characterized by
X-ray crystallography
X-ray crystallography is the experimental science determining the atomic and molecular structure of a crystal, in which the crystalline structure causes a beam of incident X-rays to diffract into many specific directions. By measuring the angles ...
, which established that the anionic complex features three bidentate (κ
2-) carbonate ligands.
To some extent, the exact description of the title salt is unimportant since it is only used as a synthetic intermediate, it has no intrinsic value. Products include
o(H2O)6sup>3+,
o(κ2-CO3)(H2O)4sup>+, and
o(κ2-CO3)2(H2O)2sup>- and their derivatives where the
aquo ligand
In chemistry, metal aquo complexes are coordination compounds containing metal ions with only water as a ligand. These complexes are the predominant species in aqueous solutions of many metal salts, such as metal nitrates, sulfates, and perchlorat ...
has been displaced.
[ The closely related potassium tris(carbonatocobalt(III) has also been used for the preparation of diverse complexes. These derivatives include o(NH3)2(κ2-CO3)2sup>- and o(CN)2(κ2-CO3)2sup>3-, rare examples of biscarbonato cobalt(III) complexes. Other derivatives include the dinitrite o(NH3)2(κ2-CO3)(NO2)2sup>- and the oxalate o(NH3)2(κ2-CO3)(C2O4)sup>-.]
Other literature
*{{cite journal , doi=10.1021/ja01504a004, title=A General Synthesis of Cobalt(III) Complexes; A New Intermediate, Na3[Co(CO3)3]·3H2O , year=1960 , last1=Bauer , first1=H. F. , last2=Drinkard , first2=W. C. , journal=Journal of the American Chemical Society , volume=82 , issue=19 , pages=5031–5032
References
Cobalt complexes
Cobalt(III) compounds
Inorganic compounds
Carbonates
Octahedral compounds
Ammine complexes