Sodium tris(carbonato)cobalt(III) is the
inorganic compound
An inorganic compound is typically a chemical compound that lacks carbon–hydrogen bondsthat is, a compound that is not an organic compound. The study of inorganic compounds is a subfield of chemistry known as ''inorganic chemistry''.
Inorgan ...
with the formula Na
3Co(CO
3)
3•3H
2O. The salt contains an olive-green metastable cobalt(III)
coordination complex
A coordination complex is a chemical compound consisting of a central atom or ion, which is usually metallic and is called the ''coordination centre'', and a surrounding array of chemical bond, bound molecules or ions, that are in turn known as ' ...
. The salt, a
homoleptic metal carbonato complex, 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 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)6 o(κ2-CO3)3 This salt has been characterized by
X-ray crystallography
X-ray crystallography is the experimental science of determining the atomic and molecular structure of a crystal, in which the crystalline structure causes a beam of incident X-rays to Diffraction, diffract in specific directions. By measuring th ...
, 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 Chemical species, species in aqueous solutions of many metal Salt (chemistry), salts, such as meta ...
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
*
*Fikru Tafesse, Elias Aphane, and Elizabeth Mongadi (2009): "Determination of the structural formula of sodium tris-carbonatocobaltate(III), Na3 o(CO3)33H2O by thermogravimetry". ''Journal of Thermal Analysis and Calorimetry'', volume 102, issue 1, pages 91–97.
*Thomas P. McCutcheon and William J. Schuele (1953): "Complex Acids of Cobalt and Chromium. The Green Carbonatocobalt(III) Anion". ''Journal of the American Chemical Society'', volume 75, issue 8, pages 1845–1846. {{doi, 10.1021/ja01104a019
References
Cobalt complexes
Cobalt(III) compounds
Inorganic compounds
Carbonato complexes
Octahedral compounds
Ammine complexes