Tetramminecopper(II) sulfate

Tetramminecopper(II) sulfate
IUPAC name Tetraamminecopper(II) sulfate monohydrate
Other names cuprammonium(II) sulfate; cupric sulfate, ammoniated
Identifiers
CAS number	14283-05-7 Y
PubChem	61513
Properties
Molecular formula	[Cu(NH3)4(H2O)n]SO4
Molar mass	245.79 g/mol
Appearance	dark blue-purple solution or crystals
Y (verify) (what is: Y/N?) Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa)
Infobox references

Tetraamminecopper(II) sulfate is the inorganic compound with the formula [Cu(NH₃)₄(H₂O)_n]SO₄. This dark blue solid is a metal complex. It is closely related to Schweizer's reagent, which is useful for the production of cellulose fibers in the production of rayon.

Preparation, structure, properties

This compound can be prepared by treating concentrated ammonia solution, NH₃, to a saturated aqueous solution of copper sulfate [Cu(H₂O)₆]SO₄ until all the copper(II) hydroxide that is initially formed redissolves into a deep blue solution. The deep blue crystalline solid tends to hydrolyze and lose ammonia ligands upon standing in air.

In the solid state, the salt consists of the [Cu(NH₃)₄H₂O]²⁺ cation, which has a square pyramidal molecular geometry. The Cu-N and Cu-O distances are about 210 and 233 pm.

Corrosion

The charactersitic deep blue colour of the tetraamine complex is found in brass and copper alloys where attack from ammonia has occurred leading to cracking. The problem was first found in ammunition cartridge cases when they were stored near animal waste, which produced trace amounts of ammonia. It is known as season cracking.

A container containing an ammonia solution of tetraamminecopper(II) sulfate

External links

• National Pollutant Inventory - Copper and compounds fact sheet
• Material Safety Data Sheet (MSDS)