Roussin's black salt

Roussin's Black Salt

240 px
264 px
Names
Other names Sodium heptanitrosyltri-μ3-thiotetraferrate
Identifiers
CAS Number	12518-87-5
Properties
Chemical formula	Fe4N7NaO7S3
Molar mass	552.67 g/mol
Appearance	Black needles
Melting point	198 to 200 °C (388 to 392 °F; 471 to 473 K)
Vapor pressure	{{{value}}}
Related compounds
Related	Roussin's Red Salt
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Infobox references

Roussin's black salt is a chemical compound with the formula NaFe₄S₃(NO)₇ first described by Zacharie Roussin. It consists of the sodium salt of the [Fe₄S₃(NO)₇]⁻ anion and is classified as metal nitrosyl compound. The cluster anion has the geometry of an incomplete cubane with C_3v symmetry. The dark colour of the complex is attributed to a number of charge-transfer interactions.

Synthesis

Roussin’s Black Salt is produced by the reaction of nitrous acid, potassium hydroxide, potassium sulfide, and iron(II) sulfate in aqueous solution. It can also be formed by the conversion of Roussin's Red Salt in mildly acidic conditions. This reaction is reversible and Roussin’s Red Salt is reformed upon alkalization of the reaction solution.

Uses

Roussin’s Black Salt is a nitric oxide donor. The nitric oxide donated by Roussin’s Black Salt has proven to be toxic to some melanoma cancer cells. Also, Roussin’s Black Salt exhibits antibacterial activity in some food processing applications.

See also

• Roussin's Red Salt