Roussin's Red Salt

Chembox new
Name = Roussin's Red Salt
ImageFile = RRSalt.png ImageFile1 = Roussin's-red-salt-anion-3D-balls.png IUPACName = potassium tetranitrosyl-di-μ-sulfidodiiron("Fe"–"Fe")(2–)
OtherNames = Ferrate(2-), tetranitrosyldi-mu-thioxodi-, (Fe-Fe), dipotassium
Section1 = Chembox Identifiers
CASNo = 58204-17-4
Section2 = Chembox Properties
Formula = Fe₂N₄K₂O₄S₂
MolarMass = 374.04 g/mol
Appearance = Dark red crystals
Density =
Solubility =
MeltingPt =
BoilingPt =
Section3 = Chembox Hazards
RPhrases =
SPhrases =

Roussin’s Red Salt is the inorganic compound with the formula K₂] [Fe₂S₂(NO)₄] . This metal nitrosyl consists of the potassium salt of the [Fe₂N₄O₄S₂] ²⁻ anion. This compound was first described in 1858 by the French chemist M.L. Roussin while experimenting with reactions between nitroprusside ion, [Fe(CN)₅NO] ²⁻, and sulfur, making it the first synthetic iron-sulfur cluster. [cite journal
title = Recherches sur les nitrosulfures doubles de fer (nouvelle classe de sels)
author = Roussin, M. L.
journal = Ann. Chim. Phys.
volume = 52
issue =
pages = 285–303
year = 1858
url = http://gallica.bnf.fr/ark:/12148/bpt6k347939/f284.table
doi = ]

tructure and bonding

Roussin's red salt anion is an example of a ligand-bridged metal dimer. Its structure is described as an edge-shared bitetrahedron, wherein a pair Fe(NO)₂ units are bridged by a pair of sulfide ligands. The Fe-NO bonds are linear indicating NO is acting as a three electron donor. [Thomas, J., Robertson, J., & Cox E. (1958). The Crystal Structure of Roussin’s Red Ethyl Ester. Acta Crystallographica, 11, 599.] The diamagnetic compound obeys the 18-electron rule, and each iron center is assigned the oxidation state of Fe(-I).

It is found in nature as its “esters" with the formula Fe₂(SR)₂(NO)₄, where "R" is any alkyl group [1] . In addition Roussin’s red salt is discussed in the fields of microbiology and food science due to its mutagenic properties. [Greenwood, N. N.; & Earnshaw, A. (1997). Chemistry of the Elements (2nd Edn.), Oxford:Butterworth-Heinemann. ISBN 0-7506-3365-4.]

ynthesis

The Roussin’s red salt can be prepared by the reaction of sulfide salts with iron nitrosyl halides: [cite journal
title = Roussin's Red Salt revisited: reactivity of Fe2 (. mu.-E) 2 (NO) 42-(E= S, Se, Te) and related
author = TB Rauchfuss, TD Weatherill
journal = Inorganic Chemistry
volume = 21
issue =
pages = 827–830
year = 1982
url = http://pubs.acs.org/cgi-bin/abstract.cgi/inocaj/1982/21/i02/f-pdf/f_ic00132a071.pdf?sessid=6006l3
doi = ] :Fe₂I₂(NO)₄ + 2Li₂S → Li₂Fe₂S₂(NO)₄ + 2LiI

To obtain the esters, the salt is alkylated::Li₂Fe₂S₂(NO)₄ + 2 RX → Fe₂(SR)₂(NO)₄ + 2 LiX

Esters can also be easily be prepared from the reaction of Fe₂I₂(NO)₄ with the thiol.

Potential applications

Today one common use of Roussin's red salt is of the ester derivative. This class of compounds is being investigated as a nitric oxide donor in biology and medicine. Due to its relatively low toxicity and good stability Roussin’s red salt can act as a possible chemotherapeutic. Photolysis of the compound induces the release of NO, thereby sensitizing target cells to exposure to radiation [2] .

ee also

Roussin's black salt

References

See also
*cite journal
title = Über komplexe Stickoxydverbindungen und das sogenannte einwertige Eisen (p 71-82)
author = Hans Reihlen, Adolf v. Friedolsheim
journal = Justus Liebig's Annalen der Chemie
volume = 457
issue =
pages = 71
year = 1927
url = http://gallica.bnf.fr/ark:/12148/bpt6k347939/f284.table
doi = 10.1002/jlac.19274570103