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Quintuple Bond
A quintuple bond in chemistry is an unusual type of chemical bond, first reported in 2005 for a dichromium compound. Single bonds, double bonds, and triple bonds are commonplace in chemistry. Quadruple bonds are rarer but are currently known only among the transition metals, especially for Cr, Mo, W, and Re, e.g. o2Cl8sup>4− and e2Cl8sup>2−. In a quintuple bond, ten electrons participate in bonding between the two metal centers, allocated as σ2π4δ4. In some cases of high-order bonds between metal atoms, the metal-metal bonding is facilitated by ligands that link the two metal centers and reduce the interatomic distance. By contrast, the chromium dimer with quintuple bonding is stabilized by a bulky terphenyl (2,6- 2,6-diisopropyl)phenylhenyl) ligands. The species is stable up to 200 °C. The chromium–chromium quintuple bond has been analyzed with multireference ''ab initio'' and DFT methods, which were also used to elucidate the role of the terphenyl ligand, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ar2Cr2PP
AR, Ar, or A&R may refer to: Arts, entertainment, and media Music * Artists and repertoire Periodicals * '' Absolute Return + Alpha'', a hedge fund publication *''The Adelaide Review'', an Australian arts magazine * ''American Renaissance'' (magazine), a white nationalist magazine and website * ''Architectural Review'', a British architectural journal * '' Armeerundschau'', a magazine of the East German army Other media * Ar, city on the fictional planet Gor * ''a.r.'' group of Polish artists and poets, including Katarzyna Kobro * Alternate reality (other), various fictional concepts Business * Accounts receivable, abbreviated as AR or A/R * Acoustic Research, an American audio electronics manufacturer * Aerojet Rocketdyne, an American aerospace and defense manufacturer * Aerolíneas Argentinas (IATA airline code AR) * Some Alfa Romeo car models, e.g. AR51 * Toyota AR engine Language * ''Ar'', the Latin letter R when spelled out * Ar (cuneiform), a cuneiform com ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Molecular Geometry
Molecular geometry is the three-dimensional arrangement of the atoms that constitute a molecule. It includes the general shape of the molecule as well as bond lengths, bond angles, torsional angles and any other geometrical parameters that determine the position of each atom. Molecular geometry influences several properties of a substance including its reactivity, polarity, phase of matter, color, magnetism and biological activity. The angles between bonds that an atom forms depend only weakly on the rest of molecule, i.e. they can be understood as approximately local and hence transferable properties. Determination The molecular geometry can be determined by various spectroscopic methods and diffraction methods. IR, microwave and Raman spectroscopy can give information about the molecule geometry from the details of the vibrational and rotational absorbance detected by these techniques. X-ray crystallography, neutron diffraction and electron diffraction can give molecu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sigma Bond
In chemistry, sigma bonds (σ bonds) are the strongest type of covalent chemical bond. They are formed by head-on overlapping between atomic orbitals. Sigma bonding is most simply defined for diatomic molecules using the language and tools of symmetry groups. In this formal approach, a σ-bond is symmetrical with respect to rotation about the bond axis. By this definition, common forms of sigma bonds are s+s, pz+pz, s+pz and dz2+dz2 (where z is defined as the axis of the bond or the internuclear axis). Quantum theory also indicates that molecular orbitals (MO) of identical symmetry actually mix or ''hybridize''. As a practical consequence of this mixing of diatomic molecules, the wavefunctions s+s and pz+pz molecular orbitals become blended. The extent of this mixing (or hybridization or blending) depends on the relative energies of the MOs of like symmetry. For homodiatomics ( homonuclear diatomic molecules), bonding σ orbitals have no nodal planes at which the wavefunction ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mo Quintuple Bond Synthesis3
Mo or MO may refer to: Arts and entertainment Fictional characters * Mo, a girl in the ''Horrible Histories'' TV series * Mo, also known as Mortimer, in the novel ''Inkheart'' by Cornelia Funke * Mo, in the webcomic '' Jesus and Mo'' * Mo, the main character in the '' Mo's Mischief'' children's book series * Mo, an ophthalmosaurus from ''The Land Before Time'' franchise * MO (Maintenance Operator), a robot in the Filmation series '' Young Sentinels'' * Mo, a main character in ''Zoey's Extraordinary Playlist'' * M-O (Microbe Obliterator), a robot in film ''WALL-E'' * Mo the clown, a character played by Roy Rene, 20th-century Australian stage comedian * Mo Effanga, in the BBC medical drama series ''Holby City'' * Mo Harris, in the BBC soap opera ''EastEnders'' * Little Mo Mitchell, in the BBC soap opera ''EastEnders'' Films * "Mo" (魔 demon), original title of '' The Boxer's Omen'', a 1983 Hong Kong film * ''Mo'' (2010 film), a television movie about British politician Mo Mo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Potassium Octachlorodimolybdate
Potassium octachlorodimolybdate (systematically named potassium bis(tetrachloromolybdate)(''Mo''–''Mo'')(4−)) is an inorganic compound with the chemical formula . It is known as a red-coloured, microcrystalline solid. The anion is of historic interest as one of the earliest illustrations of a quadruple bonding. The salt is usually obtained as the pink-coloured dihydrate. The compound is prepared in two steps from molybdenum hexacarbonyl: : : The reaction of the acetate with HCl was first described as providing trimolybdenum compounds, but subsequent crystallographic analysis confirmed that the salt contains the anion, with D4h symmetry, in which the two Mo atoms are linked by a quadruple bond. Each Mo atom is bounded with four ligands by a single bond. Each group is an regular square pyramid, with Mo atom at the apex, and four Cl atoms at the vertices of the square base of the pyramid A pyramid (from el, πυραμίς ') is a structure whose outer surfaces a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Amide
In organic chemistry, an amide, also known as an organic amide or a carboxamide, is a compound with the general formula , where R, R', and R″ represent organic groups or hydrogen atoms. The amide group is called a peptide bond when it is part of the main chain of a protein, and an isopeptide bond when it occurs in a side chain, such as in the amino acids asparagine and glutamine. It can be viewed as a derivative of a carboxylic acid () with the hydroxyl group () replaced by an amine group (); or, equivalently, an acyl (alkanoyl) group () joined to an amine group. Common examples of amides are acetamide (), benzamide (), and dimethylformamide (). Amides are qualified as primary, secondary, and tertiary according to whether the amine subgroup has the form , , or , where R and R' are groups other than hydrogen. The core of amides is called the amide group (specifically, carboxamide group). Amides are pervasive in nature and technology. Proteins and importa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Quintuple Bond Synthesis
In mathematics, a tuple is a finite ordered list (sequence) of elements. An -tuple is a sequence (or ordered list) of elements, where is a non-negative integer. There is only one 0-tuple, referred to as ''the empty tuple''. An -tuple is defined inductively using the construction of an ordered pair. Mathematicians usually write tuples by listing the elements within parentheses "" and separated by a comma and a space; for example, denotes a 5-tuple. Sometimes other symbols are used to surround the elements, such as square brackets "nbsp; or angle brackets "⟨ ⟩". Braces "" are used to specify arrays in some programming languages but not in mathematical expressions, as they are the standard notation for sets. The term ''tuple'' can often occur when discussing other mathematical objects, such as vectors. In computer science, tuples come in many forms. Most typed functional programming languages implement tuples directly as product types, tightly associated with algeb ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Valence Electron
In chemistry and physics, a valence electron is an electron in the outer shell associated with an atom, and that can participate in the formation of a chemical bond if the outer shell is not closed. In a single covalent bond, a shared pair forms with both atoms in the bond each contributing one valence electron. The presence of valence electrons can determine the element's chemical properties, such as its valence—whether it may bond with other elements and, if so, how readily and with how many. In this way, a given element's reactivity is highly dependent upon its electronic configuration. For a main-group element, a valence electron can exist only in the outermost electron shell; for a transition metal, a valence electron can also be in an inner shell. An atom with a closed shell of valence electrons (corresponding to a noble gas configuration) tends to be chemically inert. Atoms with one or two valence electrons more than a closed shell are highly reactive due to th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Potassium Graphite
Graphite intercalation compounds are complex materials having a formula where the ion or is inserted ( intercalated) between the oppositely charged carbon layers. Typically ''m'' is much less than 1. These materials are deeply colored solids that exhibit a range of electrical and redox properties of potential applications. Preparation and structure These materials are prepared by treating graphite with a strong oxidant or a strong reducing agent: : The reaction is reversible. The host (graphite) and the guest X interact by charge transfer. An analogous process is the basis of commercial lithium-ion batteries. In a graphite intercalation compound not every layer is necessarily occupied by guests. In so-called ''stage 1 compounds'', graphite layers and intercalated layers alternate and in ''stage 2 compounds'', two graphite layers with no guest material in between alternate with an intercalated layer. The actual composition may vary and therefore these compounds are an example ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Amidinate
Amidines are organic compounds with the functional group RC(NR)NR2, where the R groups can be the same or different. They are the imine derivatives of amides (RC(O)NR2). The simplest amidine is formamidine, HC(=NH)NH2. Examples of amidines include: * DBU * diminazene * benzamidine * Pentamidine * Paranyline Preparation A common route to primary amidines is the Pinner reaction. Reaction of the nitrile with alcohol in the presence of acid gives an iminoether. Treatment of the resulting compound with ammonia then completes the conversion to the amidine. Instead of using a Bronsted acid, Lewis acids such as aluminium trichloride promote the direct amination of nitriles. They are also generated by amination of an imidoyl chloride. They are also prepared by the addition of organolithium reagents to diimines, followed by protonation or alkylation. Dimethylformamide acetal reacts with primary amines to give amidines: :Me2NC(H)(OMe)2 + RNH2 → Me2NC=NHR + 2 MeOH Properties and applica ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nature (journal)
''Nature'' is a British weekly scientific journal founded and based in London, England. As a multidisciplinary publication, ''Nature'' features peer-reviewed research from a variety of academic disciplines, mainly in science and technology. It has core editorial offices across the United States, continental Europe, and Asia under the international scientific publishing company Springer Nature. ''Nature'' was one of the world's most cited scientific journals by the Science Edition of the 2019 '' Journal Citation Reports'' (with an ascribed impact factor of 42.778), making it one of the world's most-read and most prestigious academic journals. , it claimed an online readership of about three million unique readers per month. Founded in autumn 1869, ''Nature'' was first circulated by Norman Lockyer and Alexander Macmillan as a public forum for scientific innovations. The mid-20th century facilitated an editorial expansion for the journal; ''Nature'' redoubled its efforts in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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