Cobalt(II) phosphate

(Redirected from Cobalt violet)

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]

Cobalt(II) phosphate
Names
Other names
cobalt violet, cobalt(II) phosphate, cobalt orthophosphate, Pigment Violet 14
Identifiers
3D model (JSmol)
ChemSpider
ECHA InfoCard100.033.309 Edit this at Wikidata
EC Number
  • 236-655-6
UNII
  • 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
  • InChI=1/3Co.2H3O4P/c;;;2*1-5(2,3)4/h;;;2*(H3,1,2,3,4)/q3*+2;;/p-6
    Key: ZBDSFTZNNQNSQM-CYFPFDDLAU
  • [O-]P(=O)([O-])[O-].[O-]P(=O)([O-])[O-].[Co+2].[Co+2].[Co+2]
Properties
Co3(PO4)2
Molar mass366.74231 g/mol
Appearanceviolet solid
Density3.81 g/cm3
Melting point1,160 °C (2,120 °F; 1,430 K)
insoluble
2.05×10−35[1]
28,110.0·10−6 cm3/mol
1.7
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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]

See also

References