Roussin's red salt is the
inorganic compound
In chemistry, an inorganic compound is typically a chemical compound that lacks carbon–hydrogen bonds, that is, a compound that is not an organic compound. The study of inorganic compounds is a subfield of chemistry known as '' inorganic chemist ...
with the formula K
2 e2S2(NO)4 This
metal nitrosyl
Sodium nitroprusside, a medicinally significant metal nitrosyl-pentacyanoferrate (Fe-III) compound, used to treat hypertension.
Metal nitrosyl complexes are complex (chemistry), complexes that contain nitric oxide, NO, bonded to a transition me ...
was first described by Zacharie Roussin in 1858, making it one of the first synthetic
iron-sulfur clusters
Iron–sulfur proteins (or iron–sulphur proteins in British spelling) are proteins characterized by the presence of iron–sulfur clusters containing sulfide-linked di-, tri-, and tetrairon centers in variable oxidation states. Iron–sulfur clu ...
.
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
sulfide
Sulfide (British English also sulphide) is an inorganic anion of sulfur with the chemical formula S2− or a compound containing one or more S2− ions. Solutions of sulfide salts are corrosive. ''Sulfide'' also refers to chemical compounds lar ...
ligands. The Fe-
NO bonds are linear indicating NO is acting as a three electron donor.
The
diamagnetic
Diamagnetic materials are repelled by a magnetic field; an applied magnetic field creates an induced magnetic field in them in the opposite direction, causing a repulsive force. In contrast, paramagnetic and ferromagnetic materials are attracted ...
compound obeys the
18-electron rule. The dark red colour of the complex is attributed to a number of
charge-transfer interactions between the iron core and nitrosyl ligands.
Synthesis
The French chemist Z. Roussin first prepared this salt while investigating reactions between
nitroprusside
Sodium nitroprusside (SNP), sold under the brand name Nitropress among others, is a medication used to lower blood pressure. This may be done if the blood pressure is very high and resulting in symptoms, in certain types of heart failure, and d ...
ion (
e(CN)5NOsup>2−) and sulfur. The salt can be prepared by the reaction of sulfide salts with iron nitrosyl halides:
:Fe
2I
2(NO)
4 + 2Li
2S → Li
2Fe
2S
2(NO)
4 + 2LiI
To obtain the "esters", the salt is alkylated:
:Li
2Fe
2S
2(NO)
4 + 2 RX → Fe
2(SR)
2(NO)
4 + 2 LiX
Esters can also be easily be prepared from the reaction of Fe
2I
2(NO)
4 with the
thiol
In organic chemistry, a thiol (; ), or thiol derivative, is any organosulfur compound of the form , where R represents an alkyl or other organic substituent. The functional group itself is referred to as either a thiol group or a sulfhydryl gro ...
.
Occurrence and potential applications
It is found in nature as its "esters" with the formula Fe
2(SR)
2(NO)
4, where "R" is any alkyl group.
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. .]
The ester derivative are being investigated as
nitric oxide
Nitric oxide (nitrogen oxide or nitrogen monoxide) is a colorless gas with the formula . It is one of the principal oxides of nitrogen. Nitric oxide is a free radical: it has an unpaired electron, which is sometimes denoted by a dot in its che ...
donors in biology and medicine, due to the relatively low toxicity and good stability of Roussin's red salt.
Photodissociation
Photodissociation, photolysis, photodecomposition, or photofragmentation is a chemical reaction in which molecules of a chemical compound are broken down by photons. It is defined as the interaction of one or more photons with one target molecule. ...
of the compound induces the release of NO, thereby sensitizing target cells to exposure to radiation.
See also
*
Roussin's black salt
Roussin's black salt is a chemical compound with the formula KFe4S3(NO)7. It consists of the potassium salt of the e4S3(NO)7sup>− anion, metal nitrosyl compound. First described by Zacharie Roussin in 1858, it is one of the first synthetic iro ...
References
{{Nitric oxide signaling
Iron complexes
Sulfur compounds
Nitrosyl complexes