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Dicarbollide
In organometallic chemistry, a dicarbollide is an anion of the formula 2B9H11sup>2-. Various isomers exist, but most common is 1,2-dicarbollide derived from ortho-carborane. These dianions function as ligands, related to the cyclopentadienyl anion. Substituted dicarbollides are also known such as 2B9H10(pyridine)sup>− (pyridine bonded to B) and 2R2B9H9sup>2- (R groups bonded to carbon). Synthesis of dicarbollides Dicarbollides are obtained by base-degradation of 12-vertex dicarboranes. This degradation of the ortho derivative has been most heavily studied. The conversion is conducted in two-steps, first "deboronation" and second deprotonation: :C2B10H12 + NaOEt + 2 EtOH → Na+C2B9H12− + H2 + B(OEt)3 :Na+C2B9H12− + NaH → Na2C2B9H11 + H2 The dianion derived from ortho-carborane, 2B9H11sup>2- is a nido cluster. The nomenclature rules call the high coordination number vertex as 1. Thus the nido cluster with two adjacent carbon centers on the rim is ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ortho-carborane
Ortho-carborane is the organoboron compound with the formula C2B10H12. The prefix ''ortho'' is derived from ortho. It is the most prominent carborane. This derivative has been considered for a wide range of applications from heat-resistant polymers to medical applications. It is a colorless solid that melts, without decomposition, at 320 °C. Structure The cluster has C2v symmetry. Preparation Ortho-carborane is prepared by the addition of acetylenes to decaborane(14). Modern syntheses involve two stages, the first involving generation of an adduct of decaborane: :B10H14 + 2 SEt2 → B10H12(SEt2)2 + H2 In the second stage, the alkyne is installed as the source of two carbon vertices: :B10H12(SEt2)2 + C2H2 → C2B10H12 + 2 SEt2 + H2 Substituted acetylenes can be employed more conveniently than acetylene gas. For example bis(acetoxymethyl)acetylene adds to the decarborane readily. :B10H12(SEt2)2 + C2(CH2O2CCH3)2 → C2B10H10(CH2O2CCH3)2 + 2 SEt2 + H2 The organic subs ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Carborane
Carboranes are electron-delocalized (non-classically bonded) clusters composed of boron, carbon and hydrogen atoms.Grimes, R. N., ''Carboranes 3rd Ed.'', Elsevier, Amsterdam and New York (2016), . Like many of the related boron hydrides, these clusters are polyhedra or fragments of polyhedra. Carboranes are one class of heteroboranes. In terms of scope, carboranes can have as few as 5 and as many as 14 atoms in the cage framework. The majority have two cage carbon atoms. The corresponding C-alkyl and B-alkyl analogues are also known in a few cases. Structure and bonding Carboranes and boranes adopt 3-dimensional cage (cluster) geometries in sharp contrast to typical organic compounds. Cages are compatible with sigma—delocalized bonding, whereas hydrocarbons are typically chains or rings. Like for other electron-delocalized polyhedral clusters, the electronic structure of these cluster compounds can be described by the Wade–Mingos rules. Like the related boron hydrides, th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sandwich Complex
In organometallic chemistry, a sandwich compound is a chemical compound featuring a metal bound by haptic, covalent bonds to two arene (ring) ligands. The arenes have the formula , substituted derivatives (for example ) and heterocyclic derivatives (for example ). Because the metal is usually situated between the two rings, it is said to be "sandwiched". A special class of sandwich complexes are the metallocenes. The term ''sandwich compound'' was introduced in organometallic nomenclature in 1956 in a report by J. D. Dunitz, L. E. Orgel and R. A. Rich, who confirmed the structure of ferrocene by X-ray crystallography. The correct structure, in which the molecule features an iron atom ''sandwiched'' between two parallel cyclopentadienyl rings, had been proposed several years previously by Robert Burns Woodward and, separately, by Ernst Otto Fischer. The structure helped explain puzzles about ferrocene's conformers. This result further demonstrated the power of X- ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Numbering Nido11
There are many different numbering schemes for assigning nominal numbers to entities. These generally require an agreed set of rules, or a central coordinator. The schemes can be considered to be examples of a primary key of a database management system table, whose table definitions require a database design. In computability theory, the simplest numbering scheme is the assignment of natural numbers to a set of objects such as functions, rational numbers, graphs, or words in some formal language. A numbering can be used to transfer the idea of computability and related concepts, which are originally defined on the natural numbers using computable functions, to these different types of objects. A simple extension is to assign cardinal numbers to physical objects according to the choice of some base of reference and of measurement units for counting or measuring these objects within a given precision. In such case, numbering is a kind of classification, i.e. assigning a numeric pro ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Organometallic Chemistry
Organometallic chemistry is the study of organometallic compounds, chemical compounds containing at least one chemical bond between a carbon atom of an organic molecule and a metal, including alkali, alkaline earth, and transition metals, and sometimes broadened to include metalloids like boron, silicon, and selenium, as well. Aside from bonds to organyl fragments or molecules, bonds to 'inorganic' carbon, like carbon monoxide (metal carbonyls), cyanide, or carbide, are generally considered to be organometallic as well. Some related compounds such as transition metal hydrides and metal phosphine complexes are often included in discussions of organometallic compounds, though strictly speaking, they are not necessarily organometallic. The related but distinct term " metalorganic compound" refers to metal-containing compounds lacking direct metal-carbon bonds but which contain organic ligands. Metal β-diketonates, alkoxides, dialkylamides, and metal phosphine complexes are repres ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cyclopentadienyl Anion
In chemistry, the cyclopentadienyl anion or cyclopentadienide is an aromatic species with a formula of and abbreviated as Cp−. It is formed from the deprotonation of the molecule cyclopentadiene. Properties The cyclopentadienyl anion is a planar, cyclic, regular-pentagonal ion; it has 6 π-electrons (4''n'' + 2, where ''n'' = 1), which fulfills Hückel's rule of aromaticity. The structure shown is a composite of five resonance contributors in which each carbon atom carries part of the negative charge. Salt (chemistry), Salts of the cyclopentadienyl anion can be stable, e.g., sodium cyclopentadienide. It can also coordinate as a ligand to metal atoms, forming coordination compounds known as cyclopentadienyl complexes. Biscyclopentadienyl complexes are called metallocenes. Cyclopentadienyl, , and cyclopentadiene, , can substitute one or more hydrogens, forming derivatives having covalent bonds. (See Cyclopentadiene#Derivatives) Abbreviation The abb ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nickel Bis(dicarbollide) Redox
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] |
Salt Metathesis Reaction
A salt metathesis reaction, sometimes called a double displacement reaction, is a chemical process involving the exchange of bonds between two reacting chemical species which results in the creation of products with similar or identical bonding affiliations. This reaction is represented by the general scheme: :AB + CD -> AD + CB The bond between the reacting species can be either ionic or covalent. Classically, these reactions result in the precipitation of one product. In older literature, the term double decomposition is frequently encountered. The term double decomposition is more specifically used when at least one of the substances does not dissolve in the solvent, as the ligand or ion exchange takes place in the solid state of the reactant. For example: :AX(aq) + BY(s) → AY(aq) + BX(s). Types of reactions Counterion exchange Salt metathesis is a common technique for exchanging counterions. The choice of reactants is guided by a solubility chart or lattice energy. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ferrocene
Ferrocene is an organometallic compound with the formula . The molecule is a complex consisting of two cyclopentadienyl rings bound to a central iron atom. It is an orange solid with a camphor-like odor, that sublimes above room temperature, and is soluble in most organic solvents. It is remarkable for its stability: it is unaffected by air, water, strong bases, and can be heated to 400 °C without decomposition. In oxidizing conditions it can reversibly react with strong acids to form the ferrocenium cation . The rapid growth of organometallic chemistry is often attributed to the excitement arising from the discovery of ferrocene and its many analogues, such as metallocenes. History Discovery Ferrocene was discovered by accident thrice. The first known synthesis may have been made in the late 1940s by unknown researchers at Union Carbide, who tried to pass hot cyclopentadiene vapor through an iron pipe. The vapor reacted with the pipe wall, creating a "yellow sludg ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Organoboron Compounds
Organoborane or organoboron compounds are chemical compounds of boron and carbon that are organic derivatives of BH3, for example trialkyl boranes. Organoboron chemistry or organoborane chemistry is the chemistry of these compounds. Organoboron compounds are important reagents in organic chemistry enabling many chemical transformations, the most important one called hydroboration. Reactions of organoborates and boranes involve the transfer of a nucleophilic group attached to boron to an electrophilic center either inter- or intramolecularly. α,β-Unsaturated borates, as well as borates with a leaving group at the α position, are highly susceptible to intramolecular 1,2-migration of a group from boron to the electrophilic α position. Oxidation or protonolysis of the resulting organoboranes may generate a variety of organic products, including alcohols, carbonyl compounds, alkenes, and halides. Properties of the B-C bond The C-B bond has low polarity (the difference in electron ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
