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 chemi ...
with the formula K
2 e2S2(NO)4 This
metal nitrosyl was first described by Zacharie Roussin in 1858, making it one of the first synthetic
iron-sulfur clusters.
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 l ...
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 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 o