|
Ferricyanide
Ferricyanide is the anion e(CN)6sup>3−. It is also called hexacyanoferrate(III) and in rare, but systematic nomenclature, hexacyanidoferrate(III). The most common salt of this anion is potassium ferricyanide, a red crystalline material that is used as an oxidant in organic chemistry. Properties e(CN)6sup>3− consists of a Fe3+ center bound in octahedral geometry to six cyanide ligands. The complex has Oh symmetry. The iron is low spin and easily reduced to the related ferrocyanide ion e(CN)6sup>4−, which is a ferrous (Fe2+) derivative. This redox couple is reversible and entails no making or breaking of Fe–C bonds: : e(CN)6sup>3− + e− ⇌ e(CN)6sup>4− This redox couple is a standard in electrochemistry. Compared to main group cyanides like potassium cyanide, ferricyanides are much less toxic because of the strong bond between the cyanide ion (CN− ) and the Fe3+. They do react with mineral acids, however, to release highly toxic hydrogen cyanide gas. Us ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Potassium Ferricyanide
Potassium ferricyanide is the chemical compound with the formula K3 e(CN)6 This bright red salt contains the octahedrally coordinated 3−.html" ;"title="e(CN)6sup>3−">e(CN)6sup>3− ion. It is soluble in water and its solution shows some green-yellow fluorescence. It was discovered in 1822 by Leopold Gmelin. Preparation Potassium ferricyanide is manufactured by passing chlorine through a solution of potassium ferrocyanide. Potassium ferricyanide separates from the solution: :2 K4 e(CN)6+ Cl2 → 2 K3 e(CN)6+ 2 KCl Structure Like other metal cyanides, solid potassium ferricyanide has a complicated polymeric structure. The polymer consists of octahedral e(CN)6sup>3− centers crosslinked with K+ ions that are bound to the CN ligands. The K+---NCFe linkages break when the solid is dissolved in water. Applications The compound is also used to harden iron and steel, in electroplating, dyeing wool, as a laboratory reagent, and as a mild oxidizing agent in organic chemist ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Potassium Ferricyanide
Potassium ferricyanide is the chemical compound with the formula K3 e(CN)6 This bright red salt contains the octahedrally coordinated 3−.html" ;"title="e(CN)6sup>3−">e(CN)6sup>3− ion. It is soluble in water and its solution shows some green-yellow fluorescence. It was discovered in 1822 by Leopold Gmelin. Preparation Potassium ferricyanide is manufactured by passing chlorine through a solution of potassium ferrocyanide. Potassium ferricyanide separates from the solution: :2 K4 e(CN)6+ Cl2 → 2 K3 e(CN)6+ 2 KCl Structure Like other metal cyanides, solid potassium ferricyanide has a complicated polymeric structure. The polymer consists of octahedral e(CN)6sup>3− centers crosslinked with K+ ions that are bound to the CN ligands. The K+---NCFe linkages break when the solid is dissolved in water. Applications The compound is also used to harden iron and steel, in electroplating, dyeing wool, as a laboratory reagent, and as a mild oxidizing agent in organic chemist ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Prussian Blue
Prussian blue (also known as Berlin blue, Brandenburg blue or, in painting, Parisian or Paris blue) is a dark blue pigment produced by oxidation of ferrous ferrocyanide salts. It has the chemical formula Fe CN)">Cyanide.html" ;"title="e(Cyanide">CN) Turnbull's blue is chemically identical, but is made from different reagents, and its slightly different color stems from different impurities and particle sizes. Prussian blue was the first modern synthetic pigment. It is prepared as a very fine colloidal dispersion, because the compound is not soluble in water. It contains variable amounts of other ions and its appearance depends sensitively on the size of the colloidal particles. The pigment is used in paints, and it is the traditional "blue" in blueprints, and became prominent in 19th-century () Japanese woodblock prints. In medicine, orally administered Prussian blue is used as an antidote for certain kinds of heavy metal poisoning, e.g., by thallium(I) and radioactive is ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ferrocyanide
Ferrocyanide is the name of the anion CN)6">cyanide.html" ;"title="e(cyanide">CN)6sup>4−. Salts of this coordination complex give yellow solutions. It is usually available as the salt potassium ferrocyanide, which has the formula K4Fe(CN)6. e(CN)6sup>4− is a diamagnetic species, featuring low-spin iron(II) center in an octahedral ligand environment. Although many salts of cyanide are highly toxic, ferro- and ferricyanides are less toxic because they tend not to release free cyanide. It is of commercial interest as a precursor to the pigment Prussian blue and, as its potassium salt, an anticaking agent. Reactions Treatment of ferrocyanide with ferric-containing salts gives the intensely coloured pigment Prussian blue (sometimes called ferric ferrocyanide and ferrous ferricyanide). Ferrocyanide reversibly oxidized by one electron, giving ferricyanide: : e(CN)6sup>4− ⇌ e(CN)6sup>3− + e− This conversion can be followed spectroscopically at 420 nm, since ferrocy ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ferrocyanide
Ferrocyanide is the name of the anion CN)6">cyanide.html" ;"title="e(cyanide">CN)6sup>4−. Salts of this coordination complex give yellow solutions. It is usually available as the salt potassium ferrocyanide, which has the formula K4Fe(CN)6. e(CN)6sup>4− is a diamagnetic species, featuring low-spin iron(II) center in an octahedral ligand environment. Although many salts of cyanide are highly toxic, ferro- and ferricyanides are less toxic because they tend not to release free cyanide. It is of commercial interest as a precursor to the pigment Prussian blue and, as its potassium salt, an anticaking agent. Reactions Treatment of ferrocyanide with ferric-containing salts gives the intensely coloured pigment Prussian blue (sometimes called ferric ferrocyanide and ferrous ferricyanide). Ferrocyanide reversibly oxidized by one electron, giving ferricyanide: : e(CN)6sup>4− ⇌ e(CN)6sup>3− + e− This conversion can be followed spectroscopically at 420 nm, since ferrocy ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Blueprints
A blueprint is a reproduction of a technical drawing or engineering drawing using a contact print process on light-sensitive sheets. Introduced by Sir John Herschel in 1842, the process allowed rapid and accurate production of an unlimited number of copies. It was widely used for over a century for the reproduction of specification drawings used in construction and industry. The blueprint process was characterized by white lines on a blue background, a negative of the original. The process was not able to reproduce color or shades of grey. The process is now obsolete. It was first largely displaced by the diazo whiteprint process, and later by large-format xerographic photocopiers. The term ''blueprint'' continues to be used less formally to refer to any floor plan (and even less formally, any type of plan). Practicing engineers, architects, and drafters often call them "drawings", “prints”, or “plans”. It has almost entirely been replaced with digital computer-aided ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Iron Complexes
Iron () is a chemical element with symbol Fe (from la, ferrum) and atomic number 26. It is a metal that belongs to the first transition series and group 8 of the periodic table. It is, by mass, the most common element on Earth, right in front of oxygen (32.1% and 30.1%, respectively), forming much of Earth's outer and inner core. It is the fourth most common element in the Earth's crust. In its metallic state, iron is rare in the Earth's crust, limited mainly to deposition by meteorites. Iron ores, by contrast, are among the most abundant in the Earth's crust, although extracting usable metal from them requires kilns or furnaces capable of reaching or higher, about higher than that required to smelt copper. Humans started to master that process in Eurasia during the 2nd millennium BCE and the use of iron tools and weapons began to displace copper alloys, in some regions, only around 1200 BCE. That event is considered the transition from the Bronze Age to the Iron Age. In ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hydrogen Cyanide
Hydrogen cyanide, sometimes called prussic acid, is a chemical compound with the formula HCN and structure . It is a colorless, extremely poisonous, and flammable liquid that boils slightly above room temperature, at . HCN is produced on an industrial scale and is a highly valued precursor to many chemical compounds ranging from polymers to pharmaceuticals. Large-scale applications are for the production of potassium cyanide and adiponitrile, used in mining and plastics, respectively. It is more toxic than solid cyanide compounds due to its volatile nature. Structure and general properties Hydrogen cyanide is a linear molecule, with a triple bond between carbon and nitrogen. The tautomer of HCN is HNC, hydrogen isocyanide. Hydrogen cyanide is weakly acidic with a p''K''a of 9.2. It partially ionizes in water solution to give the cyanide anion, CN−. A solution of hydrogen cyanide in water, represented as HCN, is called ''hydrocyanic acid''. The salts of the cyanide ani ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Low Spin
Spin states when describing transition metal coordination complexes refers to the potential spin configurations of the central metal's d electrons. For several oxidation states, metals can adopt high-spin and low-spin configurations. The ambiguity only applies to first row metals, because second- and third-row metals are invariably low-spin. These configurations can be understood through the two major models used to describe coordination complexes; crystal field theory and ligand field theory (a more advanced version based on molecular orbital theory). High-spin vs. low-spin Octahedral complexes The Δ splitting of the ''d'' orbitals plays an important role in the electron spin state of a coordination complex. Three factors affect Δ: the period (row in periodic table) of the metal ion, the charge of the metal ion, and the field strength of the complex's ligands as described by the spectrochemical series. Only octahedral complexes of first row transition metals adopt high ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cyanide
Cyanide is a naturally occurring, rapidly acting, toxic chemical that can exist in many different forms. In chemistry, a cyanide () is a chemical compound that contains a functional group. This group, known as the cyano group, consists of a carbon atom triple-bonded to a nitrogen atom. In inorganic cyanides, the cyanide group is present as the anion . Soluble salts such as sodium cyanide (NaCN) and potassium cyanide (KCN) are highly toxic. Hydrocyanic acid, also known as hydrogen cyanide, or HCN, is a highly volatile liquid that is produced on a large scale industrially. It is obtained by acidification of cyanide salts. Organic cyanides are usually called nitriles. In nitriles, the group is linked by a covalent bond to carbon. For example, in acetonitrile (), the cyanide group is bonded to methyl (). Although nitriles generally do not release cyanide ions, the cyanohydrins do and are thus rather toxic. Bonding The cyanide ion is isoelectronic with carbon monoxide a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ligand
In coordination chemistry, a ligand is an ion or molecule (functional group) that binds to a central metal atom to form a coordination complex. The bonding with the metal generally involves formal donation of one or more of the ligand's electron pairs, often through Lewis bases. The nature of metal–ligand bonding can range from covalent to ionic. Furthermore, the metal–ligand bond order can range from one to three. Ligands are viewed as Lewis bases, although rare cases are known to involve Lewis acidic "ligands". Metals and metalloids are bound to ligands in almost all circumstances, although gaseous "naked" metal ions can be generated in a high vacuum. Ligands in a complex dictate the reactivity of the central atom, including ligand substitution rates, the reactivity of the ligands themselves, and redox. Ligand selection requires critical consideration in many practical areas, including bioinorganic and medicinal chemistry, homogeneous catalysis, and environmental chemi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Symmetry Group
In group theory, the symmetry group of a geometric object is the group of all transformations under which the object is invariant, endowed with the group operation of composition. Such a transformation is an invertible mapping of the ambient space which takes the object to itself, and which preserves all the relevant structure of the object. A frequent notation for the symmetry group of an object ''X'' is ''G'' = Sym(''X''). For an object in a metric space, its symmetries form a subgroup of the isometry group of the ambient space. This article mainly considers symmetry groups in Euclidean geometry, but the concept may also be studied for more general types of geometric structure. Introduction We consider the "objects" possessing symmetry to be geometric figures, images, and patterns, such as a wallpaper pattern. For symmetry of physical objects, one may also take their physical composition as part of the pattern. (A pattern may be specified formally as a scalar field, a funct ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
4-3D-balls.png "Click for more on -> Ligand")
