Sodium tris(carbonato)cobalt(III)

Sodium tris(carbonato)cobalt(III) is the name given to the inorganic compound with the formula Na3Co(CO3)3•3H2O. The salt contains an olive-green metastable cobalt(III) coordination complex. 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.[1]

Sodium tris(carbonato)cobalt(III)
Identifiers
3D model (JSmol)
ChemSpider
  • InChI=1S/3CH2O3.Co.3Na.3H2O/c3*2-1(3)4;;;;;;;/h3*(H2,2,3,4);;;;;3*1H2/q;;;+3;3*+1;;;/p-6
    Key: RAXRATBBPMSPAF-UHFFFAOYSA-H
  • C(=O)([O-])[O-].C(=O)([O-])[O-].C(=O)([O-])[O-].[Na+].[Na+].[Na+].[Co+3].O.O.O
Properties
C3H6CoNa3O12
Molar mass 361.972 g·mol−1
Appearance green solid
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Infobox references

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.[2] The method is a modification of the synthesis of what has been described as “Co2(CO3)3”.[3]

Structure and synthetic applications

The identity of this complex anion is uncertain, suggestions include [Co(κ2-CO3)3]3-, [Co(κ1-CO3H)3(OH)3]3-, and [Co(κ2-CO3)2(κ1-CO3)(OH2)]3-. Thermal gravimetric analysis favors the presence of one aquo ligand,[4] and infra-red spectroscopy indicates the presence of both bi- and unidentate carbonate ligands. The addition of [Co(NH3)6]Cl3 to fresh solutions of sodium tris(carbonato)cobalt(III) precipitates anhydrous salt [Co(NH3)6] [Co(κ2-CO3)3]. This salt has been characterized by X-ray crystallography, which established that the anionic complex features three bidentate (κ2-) carbonate ligands.[5]

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 [Co(H2O)6]3+, [Co(κ2-CO3)(H2O)4]+, and [Co(κ2-CO3)2(H2O)2]- and their derivatives where the aquo ligand has been displaced.[5] The closely related potassium tris(carbonatocobalt(III) has also been used for the preparation of diverse complexes. These derivatives include [Co(NH3)2(κ2-CO3)2]- and [Co(CN)2(κ2-CO3)2]3-, rare examples of biscarbonato cobalt(III) complexes. Other derivatives include the dinitrite [Co(NH3)2(κ2-CO3)(NO2)2]- and the oxalate [Co(NH3)2(κ2-CO3)(C2O4)]-.[6]

Other literature
  • Bauer, H. F.; Drinkard, W. C. (1960). "A General Synthesis of Cobalt(III) Complexes; A New Intermediate, Na3[Co(CO3)3]·3H2O". Journal of the American Chemical Society. 82 (19): 5031–5032. doi:10.1021/ja01504a004.

References
  1. Krishnamurty, Kotra V.; Mc Leod Harris, Gordon.; Sastri, Vedula S. (1970). "Chemistry of the metal carbonato complexes". Chemical Reviews. 70 (2): 171–197. doi:10.1021/cr60264a001.
  2. Bauer, H. F.; Drinkard, W. C. (1966). "Sodium Tricarbonatocobaltate(III) 3-Hydrate". Inorganic Syntheses. Inorganic Syntheses. Vol. 8. pp. 202–204. doi:10.1002/9780470132395.ch53. ISBN 9780470132395.
  3. Duval, C. (1930). "Sur le Cobalticarbonate Cobaltique". Rendus Hebdomadaires des Séances de l'Académie des Sciences. 191.
  4. Tafesse, Fikru; Aphane, Elias; Mongadi, Elizabeth (2010). "Determination of the Structural Formula of Sodium Tris-Carbonatocobaltate(III), Na3[Co(CO3)3]·3H2O by Thermogravimetry". Journal of Thermal Analysis and Calorimetry. 102: 91–97. doi:10.1007/s10973-009-0606-2. S2CID 97142236.
  5. Wangila, Grant; Jordan, R.B. (2003). "A Convenient Source of Hexaaquacobalt(III)". Inorganica Chimica Acta. 343: 347–350. doi:10.1016/S0020-1693(02)01236-7.
  6. Shibata, M. (1985). "Optically Active cis-Unidentate-Dicarbonato,cis-cis-Diunidentate-Carbonato, and Unidentate Glycinato Cobalt(III) Complexes". Inorganic Syntheses. 23: 61–79. doi:10.1002/9780470132548.ch15.
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