Cobalt(II) phosphate

Cobalt(II) phosphate
Names


Other names cobalt violet, cobalt(II) phosphate, cobalt orthophosphate, Pigment Violet 14
Identifiers
CAS Number	(tetrahydrate: 10294-50-5) 13455-36-2 (tetrahydrate: 10294-50-5)^Y
3D model (JSmol)	Interactive image
ChemSpider	55523
ECHA InfoCard	100.033.309
EC Number	236-655-6
PubChem CID	61615
UNII	0B5M38T47H^Y
CompTox Dashboard (EPA)	DTXSID20893875
InChI InChI=1S/3Co.2H3O4P/c;;;21-5(2,3)4/h;;;2(H3,1,2,3,4)/q3+2;;/p-6 Key: ZBDSFTZNNQNSQM-UHFFFAOYSA-H InChI=1/3Co.2H3O4P/c;;;21-5(2,3)4/h;;;2(H3,1,2,3,4)/q3+2;;/p-6 Key: ZBDSFTZNNQNSQM-CYFPFDDLAU
SMILES [O-]P(=O)([O-])[O-].[O-]P(=O)([O-])[O-].[Co+2].[Co+2].[Co+2]
Properties
Chemical formula	Co₃(PO₄)₂
Molar mass	366.74231 g/mol
Appearance	violet solid
Density	3.81 g/cm³
Melting point	1,160 °C (2,120 °F; 1,430 K)
Solubility in water	insoluble
Solubility product (K_sp)	2.05×10⁻³⁵^[1]
Magnetic susceptibility (χ)	28,110.0·10⁻⁶ cm³/mol
Refractive index (n_D)	1.7
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). Infobox references

Chemical compound

Cobalt phosphate is the inorganic compound with the formula Co₃(PO₄)₂. It is a commercial inorganic pigment known as cobalt violet.^[2] Thin films of this material are water oxidation catalysts.^[3]

A swatch of cobalt violet, popular among the French impressionists.

Preparation and structure

The tetrahydrate Co₃(PO₄)₂•4H₂O precipitates as a solid upon mixing aqueous solutions of cobalt(II) and phosphate salts.^[4]^[5] Upon heating, the tetrahydrate converts to the anhydrous material. According to X-ray crystallography, the anhydrous Co₃(PO₄)₂ consists of discrete phosphate (PO³⁻
₄) anions that link Co²⁺
centres. The cobalt ions occupy both octahedral (six-coordinate) and pentacoordinate sites in a 1:2 ratio.^[6]^[7]

References

^ John Rumble (June 18, 2018). CRC Handbook of Chemistry and Physics (99th ed.). CRC Press. pp. 5–188. ISBN 978-1138561632.
^ Hugo Müller, Wolfgang Müller, Manfred Wehner, Heike Liewald "Artists' Colors" in Ullmann's Encyclopedia of Industrial Chemistry 2002, Wiley-VCH, Weinheim. doi:10.1002/14356007.a03_143.pub2
^ Matthew W. Kanan; Yogesh Surendranatha; Daniel G. Nocera (2009). "Cobalt–phosphate oxygen-evolving Compound". Chem. Soc. Rev. 38 (1): 109–114. doi:10.1039/B802885K. PMID 19088970.
^ Donaldson, John Dallas; Beyersmann, Detmar (2005). "Cobalt and Cobalt Compounds". Ullmann's Encyclopedia of Industrial Chemistry. doi:10.1002/14356007.a07_281.pub2. ISBN 9783527303854.
^ Sankar, Selvasundarasekar Sam; Rathishkumar, Arumugam; Geetha, Kathiresan; Kundu, Subrata (2020-10-15). "A Simple Route for the Synthesis of Cobalt Phosphate Nanoparticles for Electrocatalytic Water Oxidation in Alkaline Medium". Energy & Fuels. 34 (10): 12891–12899. doi:10.1021/acs.energyfuels.0c02809. ISSN 0887-0624. S2CID 224960926.
^ Anderson, J. B.; Kostiner, E.; Miller, M. C.; Rea, J. R. (1975). "Crystal structure of cobalt orthophosphate Co₃(PO₄)₂". Journal of Solid State Chemistry. 14 (4): 372–377. Bibcode:1975JSSCh..14..372A. doi:10.1016/0022-4596(75)90058-4.
^ Nord, A. G.; Stefanidis, T. (1983). "Structure refinements of Co₃(PO₄)₂. A Note on the Reliability of Powder Diffraction Studies". Acta Chemica Scandinavica A. 37: 715–721. doi:10.3891/acta.chem.scand.37a-0715.