Ferrocyanide
Encyclopedia
Ferrocyanide is the name of the anion Fe
(C
N
)64−. In aqueous solutions, this coordination complex is relatively unreactive. It is usually available as the salt potassium ferrocyanide
, which has the formula K4Fe(CN)6.
Ferrocyanide was not named as a compound of iron and cyanide
; rather cyanides as a chemical class were named because they were discovered in ferrocyanide. Ferrocyanide in turn was an iron
radical found in the analysis of the intensely blue dye Prussian blue
, and named in Latin to mean "blue substance with iron." The dye had been first accidentally made in the early 18th century from substances containing iron, carbon, and nitrogen, and the (then unknown) cyanide formed during the manufacture of the dye. The word "cyanide" used in the name is from kyanos, Greek for "(dark) blue." The ferrocyanide anion itself, when not complexed with iron cations, is colored a moderate yellow.
. Although many salts of cyanide are highly toxic, ferro- and ferricyanides are less toxic because they tend not to release free cyanide.
Its most important reaction is its oxidation to ferricyanide
:
This conversion can be followed spectroscopically at 535 nm with an absorption coefficient of 21600 M−1 cm−1.
Treatment of ferrocyanide with ferric-containing salts gives the intensely coloured pigment Prussian Blue
.
. Ferricyanide is used thus any increase in ferrocyanide can be attributed to secretions of reductants or "Trans Plasma Membrane Electron Transport" (TPMET) activity.
, ferrocyanide should be called "hexacyanoferrate(II)."
Iron
Iron is a chemical element with the symbol Fe and atomic number 26. It is a metal in the first transition series. It is the most common element forming the planet Earth as a whole, forming much of Earth's outer and inner core. It is the fourth most common element in the Earth's crust...
(C
Carbon
Carbon is the chemical element with symbol C and atomic number 6. As a member of group 14 on the periodic table, it is nonmetallic and tetravalent—making four electrons available to form covalent chemical bonds...
N
Nitrogen
Nitrogen is a chemical element that has the symbol N, atomic number of 7 and atomic mass 14.00674 u. Elemental nitrogen is a colorless, odorless, tasteless, and mostly inert diatomic gas at standard conditions, constituting 78.08% by volume of Earth's atmosphere...
)64−. In aqueous solutions, this coordination complex is relatively unreactive. It is usually available as the salt potassium ferrocyanide
Potassium ferrocyanide
Potassium ferrocyanide is the inorganic compound with formula K4[Fe6]•3H2O. It is the potassium salt of the coordination complex [Fe6]4-. This salt forms lemon-yellow monoclinic crystals.-Synthesis:...
, which has the formula K4Fe(CN)6.
Ferrocyanide was not named as a compound of iron and cyanide
Cyanide
A cyanide is a chemical compound that contains the cyano group, -C≡N, which consists of a carbon atom triple-bonded to a nitrogen atom. Cyanides most commonly refer to salts of the anion CN−. Most cyanides are highly toxic....
; rather cyanides as a chemical class were named because they were discovered in ferrocyanide. Ferrocyanide in turn was an iron
Iron
Iron is a chemical element with the symbol Fe and atomic number 26. It is a metal in the first transition series. It is the most common element forming the planet Earth as a whole, forming much of Earth's outer and inner core. It is the fourth most common element in the Earth's crust...
radical found in the analysis of the intensely blue dye Prussian blue
Prussian blue
Prussian blue is a dark blue pigment with the idealized formula Fe718. Another name for the color Prussian blue is Berlin blue or, in painting, Parisian blue. Turnbull's blue is the same substance but is made from different reagents....
, and named in Latin to mean "blue substance with iron." The dye had been first accidentally made in the early 18th century from substances containing iron, carbon, and nitrogen, and the (then unknown) cyanide formed during the manufacture of the dye. The word "cyanide" used in the name is from kyanos, Greek for "(dark) blue." The ferrocyanide anion itself, when not complexed with iron cations, is colored a moderate yellow.
Coordination chemistry
[Fe(CN)6]4− is a diamagnetic species, featuring low-spin iron(II) center in an octahedral ligand environmentOctahedral molecular geometry
In chemistry, octahedral molecular geometry describes the shape of compounds where in six atoms or groups of atoms or ligands are symmetrically arranged around a central atom, defining the vertices of an octahedron...
. Although many salts of cyanide are highly toxic, ferro- and ferricyanides are less toxic because they tend not to release free cyanide.
Its most important reaction is its oxidation to ferricyanide
Ferricyanide
Ferricyanide is the anion [Fe6]3−. It is also called hexacyanoferrate and in rare, but systematic nomenclature, hexacyanidoferrate...
:
- [Fe(CN)6]4−
[Fe(CN)6]3− + e−
This conversion can be followed spectroscopically at 535 nm with an absorption coefficient of 21600 M−1 cm−1.
Treatment of ferrocyanide with ferric-containing salts gives the intensely coloured pigment Prussian Blue
Prussian blue
Prussian blue is a dark blue pigment with the idealized formula Fe718. Another name for the color Prussian blue is Berlin blue or, in painting, Parisian blue. Turnbull's blue is the same substance but is made from different reagents....
.
Use in biochemical research
Ferrocyanide and its oxidized product ferricyanide, [Fe(CN)6]3−, are impermeable to the plasma membrane. For this reason ferrocyanide has been used as a probe of extracellular electron receptor in the study of redox reactions in cellsCell (biology)
The cell is the basic structural and functional unit of all known living organisms. It is the smallest unit of life that is classified as a living thing, and is often called the building block of life. The Alberts text discusses how the "cellular building blocks" move to shape developing embryos....
. Ferricyanide is used thus any increase in ferrocyanide can be attributed to secretions of reductants or "Trans Plasma Membrane Electron Transport" (TPMET) activity.
Nomenclature
According to the recommendations of IUPACIUPAC nomenclature
A chemical nomenclature is a set of rules to generate systematic names for chemical compounds. The nomenclature used most frequently worldwide is the one created and developed by the International Union of Pure and Applied Chemistry ....
, ferrocyanide should be called "hexacyanoferrate(II)."