Copper(II) phosphate

For other uses, see Copper phosphate.

Copper(II) phosphate is an inorganic compound with the chemical formula Cu₃(PO₄)₂. It can be regarded as the cupric salt of phosphoric acid. Anhydrous copper(II) phosphate and a trihydrate are blue solids.

Copper(II) phosphate

(Cu2+)3 [PO43−]2
Names
IUPAC name copper(II) phosphate
Other names tricopper diphosphate tricopper bis(orthophosphate)
Identifiers
CAS Number	7798-23-4 trihydrate Y
3D model (JSmol)	Interactive image
ChemSpider	77984 Y
ECHA InfoCard	100.029.322
PubChem CID	86469
UNII	N8NP6FR80R Y
CompTox Dashboard (EPA)	DTXSID00872547
InChI InChI=1S/3Cu.2H3O4P/c;;;2*1-5(2,3)4/h;;;2*(H3,1,2,3,4)/q3*+2;;/p-6 Key: GQDHEYWVLBJKBA-UHFFFAOYSA-H
SMILES [O-]P(=O)([O-])[O-].[O-]P(=O)([O-])[O-].[Cu+2].[Cu+2].[Cu+2]
Properties
Chemical formula	Cu3(PO4)2
Molar mass	380.580722 g/mol (anhydrous) 434.63 g/mol (trihydrate)
Appearance	light bluish-green powder (anhydrous) blue or olive crystals (trihydrate)
Solubility in water	slightly soluble[1]
Solubility product (Ksp)	1.4×10−37[2]
Solubility	anhydrous: soluble in ammonia trihydrate: soluble in ammonium hydroxide slightly soluble in acetone insoluble in ethanol
Structure
Crystal structure	orthorhombic (trihydrate)
Hazards
GHS labelling:
Pictograms
Signal word	Danger
Hazard statements	H315, H318, H410
Precautionary statements	P264, P264+P265, P273, P280, P302+P352, P305+P354+P338, P317, P321, P332+P317, P362+P364, P391, P501
NIOSH (US health exposure limits):
PEL (Permissible)	TWA 1 mg/m3 (as Cu)[3]
REL (Recommended)	TWA 1 mg/m3 (as Cu)[3]
IDLH (Immediate danger)	TWA 100 mg/m3 (as Cu)[3]
Related compounds
Other cations	Cobalt(II) phosphate Iron(II) phosphate Manganese(II) phosphate Nickel(II) phosphate
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). Infobox references

Preparation

Hydrated copper(II) phosphate precipitates upon addition of a solution of alkali metal phosphate to an aqueous solution of copper(II) sulfate.^[4] The anhydrous material can be produced by a high-temperature (1000 °C) reaction between diammonium phosphate and copper(II) oxide.^[5]

2 (NH₄)₂HPO₄ + 3 CuO → Cu₃(PO₄)₂ + 3 H₂O + 4 NH₃

In laboratories, copper phosphate is prepared by the addition of phosphoric acid to an alkali copper salt such as copper hydroxide, or basic copper carbonate.

3 Cu(OH)₂ + 2 H₃PO₄ → 6 H₂O + Cu₃(PO₄)₂

3 Cu₂(OH)₂CO₃ + 4 H₃PO₄ → 2 Cu₃(PO₄)₂ + 3 CO₂ + 9 H₂O

Uses

Copper(II) phosphate has many uses. Due to it being a copper metal salt it can be used as a fungicide; it works by denaturating proteins and enzymes in cells of pathogens. Many other copper salts, such as copper sulfate, are used as fungicides. ^[6]

Another use of copper(II) phosphate is as a fertilizer. Copper is one of the 16 essential elements required for plant growth. Copper(II) phosphate supplies the plant with both phosphorus and copper, which stimulates growth.^[7]

Structure

Structure of Cu₃(PO₄)₂(H₂O). Color code: red = O, blue = Cu, purple = P.

In terms of structure, copper(II) phosphate is a coordination polymer, as is typical for most metal phosphates. The phosphate center is tetrahedral. In the anhydrous material, the copper centers are pentacoordinate. In the monohydrate, the copper adopts 6-, 5-, and 4-coordinate geometries.^[8]

Minerals

Copper(II) phosphate is relatively commonly encountered as the hydrated species Cu₂(PO₄)OH, which is green and occurs naturally as the mineral libethenite. Pseudomalachite, Cu₅(PO₄)₂(OH)₄, is the most common copper phosphate in nature, typical for some oxidation zones of copper ore deposits.^[9][10]