Cobalt phosphate

Cobalt 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)
EC Number	236-655-6
Jmol interactive 3D	Image
PubChem	61615
InChI InChI=1S/3Co.2H3O4P/c;;;2*1-5(2,3)4/h;;;2*(H3,1,2,3,4)/q3*+2;;/p-6 Key: ZBDSFTZNNQNSQM-UHFFFAOYSA-H
SMILES [O-]P(=O)([O-])[O-].[O-]P(=O)([O-])[O-].[Co+2].[Co+2].[Co+2]
Properties
Chemical formula	Co3O8P2
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
Refractive index (nD)	1.7
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Infobox references

Cobalt phosphate is the inorganic compound with the formula Co₃(PO₄)₂. It is a commercial inorganic pigment known as cobalt violet.^[1] Thin films of this material catalyze the oxidation of water.^[2]

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

Preparation and structure

It precipitates as a solid tetrahydrate upon mixing aquous solutions of cobalt(II) and phosphate salts. The anhydrous material 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.^[3]

References

1. ↑ 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
2. ↑ Matthew W. Kanan, Yogesh Surendranatha, Daniel G. Nocera "Cobalt–phosphate oxygen-evolving compound" Chem. Soc. Rev., 2009, volume 38, 109-114. doi:10.1039/B802885K
3. ↑ Anderson, J. B.; Kostiner, E.; Miller, M. C.; Rea, J. R. "Crystal structure of cobalt orthophosphate Co₃(PO₄)₂" Journal of Solid State Chemistry 1975, vol. 14, 372-7.