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Hofmann Clathrate
In inorganic chemistry, Hofmann clathrates refers to materials with the formula Ni(CN)2(NH3)(C6H6). These materials are a type of coordination polymer. They have attracted attention because they can be used to separate xylenes. On a conceptual level, Hofmann clathrates can be viewed as forerunners to metal-organic frameworks (MOFs). Structures The empirical formula Ni(CN)2(NH3)(C6H6) reflects the presence of two types of nickel(II) centers, one of which is the square-planar tetracyanonickelate, i(CN)4sup>2-. The second kind of nickel site consists of i(NH3)2sup>2+ groups that are connected to the Ni-CN nitrogens. Thus cyanide serves as a bridging ligand. The linking of the i(CN)4sup>2- and ''trans''- i(NH3)2sup>2+ subunits results in a sheet-like polymer. Voids between these sheets, defined by the ammonia ligands, are occupied by benzene molecules. Variations Many variations of Hofmann clathrates have been reported. The ammonia ligands can be replaced by diamines. Tetra ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Inorganic Chemistry
Inorganic chemistry deals with synthesis and behavior of inorganic and organometallic compounds. This field covers chemical compounds that are not carbon-based, which are the subjects of organic chemistry. The distinction between the two disciplines is far from absolute, as there is much overlap in the subdiscipline of organometallic chemistry. It has applications in every aspect of the chemical industry, including catalysis, materials science, pigments, surfactants, coatings, medications, fuels, and agriculture. Key concepts Many inorganic compounds are ionic compounds, consisting of cations and anions joined by ionic bonding. Examples of salts (which are ionic compounds) are magnesium chloride MgCl2, which consists of magnesium cations Mg2+ and chloride anions Cl−; or sodium oxide Na2O, which consists of sodium cations Na+ and oxide anions O2−. In any salt, the proportions of the ions are such that the electric charges cancel out, so that the bulk compound is e ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Coordination Polymer
A coordination polymer is an inorganic or organometallic polymer structure containing metal cation centers linked by ligands. More formally a coordination polymer is a coordination compound with repeating coordination entities extending in 1, 2, or 3 dimensions. It can also be described as a polymer whose repeat units are coordination complexes. Coordination polymers contain the subclass coordination networks that are coordination compounds extending, through repeating coordination entities, in 1 dimension, but with cross-links between two or more individual chains, loops, or spiro-links, or a coordination compound extending through repeating coordination entities in 2 or 3 dimensions. A subclass of these are the metal-organic frameworks, or MOFs, that are coordination networks with organic ligands containing potential voids. Coordination polymers are relevant to many fields, having many potential applications. Coordination polymers can be classified in a number of ways accor ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Xylene
In organic chemistry, xylene or xylol (; IUPAC name: dimethylbenzene) are any of three organic compounds with the formula . They are derived from the substitution of two hydrogen atoms with methyl groups in a benzene ring; which hydrogens are substituted determines which of three structural isomers results. It is a colorless, flammable, slightly greasy liquid of great industrial value. The mixture is referred to as both xylene and, more precisely, xylenes. Mixed xylenes refers to a mixture of the xylenes plus ethylbenzene. The four compounds have identical empirical formulas . Typically the four compounds are produced together by various catalytic reforming and pyrolysis methods. Occurrence and production Xylenes are an important petrochemical produced by catalytic reforming and also by carbonization, coal carbonisation in the manufacture of coke (fuel), coke fuel. They also occur in crude oil in concentrations of about 0.5–1%, depending on the source. Small quantities occur ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ni(CN)2(NH3)(C6H6) (HEMJIS)
NI or Ni may refer to: Arts and entertainment * Ni, or Nishada, the seventh note of the Indian musical scale in raga * ''New Internationalist'', a magazine * Knights Who Say "Ni!", characters from the film ''Monty Python and the Holy Grail'' Businesses * National Instruments, a U.S. producer of automated test equipment and virtual instrumentation software * National Insurance, a system of taxes and related social security benefits in the United Kingdom * Native Instruments, a music software production company * News International, a British newspaper publisher * Portugália airline (IATA code NI) Language * Ni (letter), or Nu, a letter in the Greek alphabet: uppercase Ν, lowercase ν * Ni (kana), romanisation of the Japanese kana に and ニ * Ni (cuneiform), a sign in cuneiform writing Names * Ni (surname) (倪), a Chinese surname * Ní, a surname prefix from the shortened form of the Irish word for a daughter * Ni, female prefix to some Balinese names Places * Ni Rive ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tetracyanonickelate
The cyanonickelates are a class of chemical compound containing anions consisting of nickel atoms, and cyanide groups. The most important of these are the tetracyanonickelates containing four cyanide groups per nickel. The tetracyanonickelates contain the [Ni(CN)4]2− anion. This can exist in solution or in solid salts. The ion has cyanide groups arranged in a square around the central nickel ion. The symmetry of the ion is Dihedral symmetry in three dimensions, D4''h''. The distance from the nickel atom to the carbon is 1.87 Å, and the carbon-nitrogen distance is 1.16 Å. Tetracyanonickelate(II) can be oxidised electrochemically in solution to yield tetracyanonickelate(III) [Ni(CN)4]−. [Ni(CN)4]− is unstable and Ni(III) oxidises the cyanide to cyanate OCN−. Tetracyanonickelate(III) can add two more cyanide groups to form hexacyanonickelate(III). In combination with alkyldiamines, and other metal ions, tetracyanonickelate ions can form cage structure that can ac ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bridging Ligand
In coordination chemistry, a bridging ligand is a ligand that connects two or more atoms, usually metal ions. The ligand may be atomic or polyatomic. Virtually all complex organic compounds can serve as bridging ligands, so the term is usually restricted to small ligands such as pseudohalides or to ligands that are specifically designed to link two metals. In naming a complex wherein a single atom bridges two metals, the bridging ligand is preceded by the Greek letter mu, μ, with a subscript number denoting the number of metals bound to the bridging ligand. μ2 is often denoted simply as μ. When describing coordination complexes care should be taken not to confuse μ with η ('eta'), which relates to hapticity. Ligands that are not bridging are called terminal ligands. List of bridging ligands Virtually all ligands are known to bridge, with the exception of amines and ammonia. Common bridging ligands include most of the common anions. Many simple organic ligands form str ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ammonia Ligand
In coordination chemistry, metal ammine complexes are metal complexes containing at least one ammonia () ligand. "Ammine" is spelled this way due to historical reasons; in contrast, alkyl or aryl bearing ligands are spelt with a single "m". Almost all metal ions bind ammonia as a ligand, but the most prevalent examples of ammine complexes are for Cr(III), Co(III), Ni(II), Cu(II) as well as several platinum group metals.A. von Zelewsky "Stereochemistry of Coordination Compounds" John Wiley: Chichester, 1995. . History Ammine complexes played a major role in the development of coordination chemistry, specifically determination of the stereochemistry and structure. They are easily prepared, and the metal-nitrogen ratio can be determined by elemental analysis. Through studies mainly on the ammine complexes, Alfred Werner developed his Nobel Prize-winning concept of the structure of coordination compounds (see Figure). One of the first ammine complexes to be described was Magnus' green ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Diamine
A diamine is an amine with exactly two amino groups. Diamines are used as monomers to prepare polyamides, polyimides, and polyureas. The term ''diamine'' refers mostly to primary diamines, as those are the most reactive. In terms of quantities produced, 1,6-diaminohexane (a precursor to Nylon 6-6) is most important, followed by ethylenediamine. Vicinal diamines (1,2-diamines) are a structural motif in many biological compounds and are used as ligands in coordination chemistry. Aliphatic diamines Linear * 1 carbon: methylenediamine (diaminomethane) of theoretical interest only * 2 carbons: ethylenediamine (1,2-diaminoethane). Related derivatives include the N-alkylated compounds, 1,1-dimethylethylenediamine, 1,2-dimethylethylenediamine, ethambutol, tetrakis(dimethylamino)ethylene, TMEDA. File:Ethylene_diamine.png, Ethylenediamine * 3 carbons: 1,3-diaminopropane (propane-1,3-diamine) * 4 carbons: putrescine (butane-1,4-diamine) * 5 carbons: cadaverine (pentane-1,5-diamine) ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tetracyanopalladate
Palladium(II) dicyanide is the inorganic compound with the formula Pd(CN)2. A grey solid, it is a coordination polymer. It was the first palladium compound isolated in pure form. In his attempts to produce pure platinum metal in 1804, W.H. Wollaston added mercuric cyanide to a solution prepared by dissolving impure platinum in aqua regia. This precipitated palladium cyanide which was then ignited to recover palladium metal—a new element. Structure It had long been suspected that the structure of palladium cyanide consists of square planar Pd(II) centers linked by cyanide bridging ligands, which are bonded through both the carbon and nitrogen atoms. The CN vibration in the infrared spectra of Pd(CN)2, at 2222 cm−1, is typical of bridging cyanide ion. It is now known that the compound commonly known as "palladium(II) cyanide" is in fact a nanocrystaline material better described using the formula Pd(CN)2.0.29H2O. The interior of the sheets do indeed consist of square-pl ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Arene
Aromatic compounds, also known as "mono- and polycyclic aromatic hydrocarbons", are organic compounds containing one or more aromatic rings. The parent member of aromatic compounds is benzene. The word "aromatic" originates from the past grouping of molecules based on smell, before their general chemical properties are understood. The current definition of aromatic compounds does not have any relation with their smell. Heteroarenes are closely related, since at least one carbon atom of CH group is replaced by one of the heteroatoms oxygen, nitrogen, or sulfur. Examples of non-benzene compounds with aromatic properties are furan, a heterocyclic compound with a five-membered ring that includes a single oxygen atom, and pyridine, a heterocyclic compound with a six-membered ring containing one nitrogen atom. Hydrocarbons without an aromatic ring are called aliphatic. Benzene ring model Benzene, C6H6, is the least complex aromatic hydrocarbon, and it was the first one named as such ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nickel Complexes
Nickel is a chemical element with symbol Ni and atomic number 28. It is a silvery-white lustrous metal with a slight golden tinge. Nickel is a hard and ductile transition metal. Pure nickel is chemically reactive but large pieces are slow to react with air under standard conditions because a passivation layer of nickel oxide forms on the surface that prevents further corrosion. Even so, pure native nickel is found in Earth's crust only in tiny amounts, usually in ultramafic rocks, and in the interiors of larger nickel–iron meteorites that were not exposed to oxygen when outside Earth's atmosphere. Meteoric nickel is found in combination with iron, a reflection of the origin of those elements as major end products of supernova nucleosynthesis. An iron–nickel mixture is thought to compose Earth's outer and inner cores. Use of nickel (as natural meteoric nickel–iron alloy) has been traced as far back as 3500 BCE. Nickel was first isolated and classified as an ele ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
2(NH3)(C6H6)_(HEMJIS).png "Click for more on -> Hofmann Clathrate")
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