Roussin's Red Salt
Encyclopedia
Roussin’s Red Salt is the inorganic compound
with the formula K2[Fe2S2(NO)4]. This metal nitrosyl
was first described in 1858, making it the first synthetic iron-sulfur cluster
.
ligands. The Fe-NO bonds are linear indicating NO is acting as a three electron donor. The diamagnetic compound obeys the 18-electron rule
, and each iron center is assigned the oxidation state of Fe(-I).
− ) and sulfur. The salt can be prepared by the reaction of sulfide salts with iron nitrosyl halides:
To obtain the "esters", the salt is alkylated:
Esters can also be easily be prepared from the reaction of Fe2I2(NO)4 with the thiol
.
The ester derivative are being investigated as a nitric oxide
donors in biology and medicine. Due to the relatively low toxicity and good stability Roussin’s red salt. Photolysis of the compound induces the release of NO, thereby sensitizing target cells to exposure to radiation [2].
Inorganic compound
Inorganic compounds have traditionally been considered to be of inanimate, non-biological origin. In contrast, organic compounds have an explicit biological origin. However, over the past century, the classification of inorganic vs organic compounds has become less important to scientists,...
with the formula K2[Fe2S2(NO)4]. This metal nitrosyl
Metal nitrosyl
Metal nitrosyl complexes are complexes that contain nitric oxide, NO, bonded to a transition metal. Many kinds of nitrosyl complexes are known, which vary both in structure and coligand.-Bonding and structure:...
was first described in 1858, making it the first synthetic iron-sulfur cluster
Iron-sulfur cluster
For biological Fe-S clusters, see iron-sulfur proteins.Iron-sulfur clusters are ensembles of iron and sulfide centres. Fe-S clusters are most often discussed in the context of the biological role for iron-sulfur proteins. Many Fe-S clusters are known in the area of organometallic chemistry and as...
.
Structure and bonding
Roussin's red salt anion is an edge-shared bitetrahedron, wherein a pair Fe(NO)2 units are bridged by a pair of sulfideSulfide
A sulfide is an anion of sulfur in its lowest oxidation state of 2-. Sulfide is also a slightly archaic term for thioethers, a common type of organosulfur compound that are well known for their bad odors.- Properties :...
ligands. The Fe-NO bonds are linear indicating NO is acting as a three electron donor. The diamagnetic compound obeys the 18-electron rule
18-Electron rule
The 18-electron rule is a rule of thumb used primarily for predicting formulas for stable metal complexes. The rule rests on the fact that valence shells of a transition metal consists of nine valence orbitals, which collectively can accommodate 18 electrons either as nonbinding electron pairs or...
, and each iron center is assigned the oxidation state of Fe(-I).
Synthesis
The French chemist M.L. Roussin first prepared this salt while investigating reactions between nitroprusside ion ([Fe(CN)5NO]2- 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
Thiol
In organic chemistry, a thiol is an organosulfur compound that contains a carbon-bonded sulfhydryl group...
.
Occurrence and potential applications
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.The ester derivative are being investigated as a nitric oxide
Nitric oxide
Nitric oxide, also known as nitrogen monoxide, is a diatomic molecule with chemical formula NO. It is a free radical and is an important intermediate in the chemical industry...
donors in biology and medicine. Due to the relatively low toxicity and good stability Roussin’s red salt. Photolysis of the compound induces the release of NO, thereby sensitizing target cells to exposure to radiation [2].