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Fulvalene (compound Class)
A fulvalene is a hydrocarbon obtained by formally cross-conjugating two rings through a common exocyclic double bond. The name is derived from the similarly structured fulvenes which lack one ring. Pentafulvalene (2) is also called simply fulvalene, the parent structure of this class. Triapentafulvalene (3) is also known as calicene from the words ''calix'' or ''chalice'' because of its wine-glass appearance. In general, the parent fulvalenes are very unstable; for instance, the parent triafulvalene (1) has never been synthesized. On the other hand, stable fulvalenes can be obtained by proper substitution or benzannulation. Several members should be stabilized taking into account a dipolar mesomeric form with for instance sesquifulvalene 4, which can be thought of as a tropylium cation joined to a cyclopentadienyl anion (both stable and aromatic). In this compound the dipolar structure is calculated to contribute 23% to the total structure. Fulvalenes as a ligand : Tungsten fulva ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fulvalenes General
A fulvalene is a hydrocarbon obtained by formally cross-conjugating two rings through a common exocyclic double bond. The name is derived from the similarly structured fulvenes which lack one ring. Pentafulvalene (2) is also called simply fulvalene, the parent structure of this class. Triapentafulvalene (3) is also known as calicene from the words ''calix'' or ''chalice'' because of its wine-glass appearance. In general, the parent fulvalenes are very unstable; for instance, the parent triafulvalene (1) has never been synthesized. On the other hand, stable fulvalenes can be obtained by proper substitution or benzannulation. Several members should be stabilized taking into account a dipolar mesomeric form with for instance sesquifulvalene 4, which can be thought of as a tropylium cation joined to a cyclopentadienyl anion (both stable and aromatic). In this compound the dipolar structure is calculated to contribute 23% to the total structure. Fulvalenes as a ligand : Tungsten f ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Substituent
A substituent is one or a group of atoms that replaces (one or more) atoms, thereby becoming a moiety in the resultant (new) molecule. (In organic chemistry and biochemistry, the terms ''substituent'' and ''functional group'', as well as ''side chain'' and '' pendant group'', are used almost interchangeably to describe those branches from the parent structure, though certain distinctions are made in polymer chemistry. In polymers, side chains extend from the backbone structure. In proteins, side chains are attached to the alpha carbon atoms of the amino acid backbone.) The suffix ''-yl'' is used when naming organic compounds that contain a single bond replacing one hydrogen; ''-ylidene'' and ''-ylidyne'' are used with double bonds and triple bonds, respectively. In addition, when naming hydrocarbons that contain a substituent, positional numbers are used to indicate which carbon atom the substituent attaches to when such information is needed to distinguish between isomers. Su ... [...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] |
Organometallic
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] |
W2FulvaleneComplex
W, or w, is the twenty-third and fourth-to-last letter of the Latin alphabet, used in the modern English alphabet, the alphabets of other western European languages and others worldwide. It represents a consonant, but in some languages it represents a vowel. Its name in English is ''double-u'',Pronounced in formal situations, but colloquially often , , or , with a silent ''l''. plural ''double-ues''. History The classical Latin alphabet, from which the modern European alphabets derived, did not have the "W' character. The "W" sounds were represented by the Latin letter " V" (at the time, not yet distinct from " U"). The sounds (spelled ) and (spelled ) of Classical Latin developed into a bilabial fricative between vowels in Early Medieval Latin. Therefore, no longer adequately represented the labial-velar approximant sound of Germanic phonology. The Germanic phoneme was therefore written as or ( and becoming distinct only by the Early Modern period) b ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Aromatic
In chemistry, aromaticity is a chemical property of cyclic ( ring-shaped), ''typically'' planar (flat) molecular structures with pi bonds in resonance (those containing delocalized electrons) that gives increased stability compared to saturated compounds having single bonds, and other geometric or connective non-cyclic arrangements with the same set of atoms. Aromatic rings are very stable and do not break apart easily. Organic compounds that are not aromatic are classified as aliphatic compounds—they might be cyclic, but only aromatic rings have enhanced stability. The term ''aromaticity'' with this meaning is historically related to the concept of having an aroma, but is a distinct property from that meaning. Since the most common aromatic compounds are derivatives of benzene (an aromatic hydrocarbon common in petroleum and its distillates), the word ''aromatic'' occasionally refers informally to benzene derivatives, and so it was first defined. Nevertheless, many ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cyclopentadienyl
{{Chemistry index ...
Cyclopentadienyl can refer to *Cyclopentadienyl anion, or cyclopentadienide, **Cyclopentadienyl ligand *Cyclopentadienyl radical, • *Cyclopentadienyl cation, See also *Pentadienyl In organic chemistry, pentadienyl refers to the organic radical, anion, or cation with the formula , where ''z'' = 0, −1, +1, respectively. Organometallic chemistry In organometallic chemistry, the pentadienyl anion is a ligand, the acyclic ana ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tropylium Cation
In organic chemistry, the tropylium ion or cycloheptatrienyl cation is an aromatic species with a formula of 7H7sup>+. Its name derives from the molecule tropine from which cycloheptatriene (tropylidene) was first synthesized in 1881. Salts of the tropylium cation can be stable, even with nucleophiles of moderate strength e.g., tropylium tetrafluoroborate and tropylium bromide (''see below''). Its bromide and chloride salts can be made from cycloheptatriene and bromine or phosphorus pentachloride, respectively. It is a regular heptagonal, planar, cyclic ion. It has 6 π-electrons (4''n'' + 2, where ''n'' = 1), which fulfills Hückel's rule of aromaticity. It can coordinate as a ligand to metal atoms. The structure shown is a composite of seven resonance contributors in which each carbon atom carries part of the positive charge. History In 1891 G. Merling obtained a water-soluble bromine-containing compound from the reaction of cycloheptatriene and bromine. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sesquifulvalene
Sesquifulvalene or Pentaheptafulvalene is a hydrocarbon in the fulvalene class with chemical formula C12H10. It is composed of linked cyclopentadiene and cycloheptatriene rings. Properties In the ground state, which is a singlet state, the central double bond is polarized, with a partial positive charge on the carbon atom of heptagonal ring and a partial negative charge on the carbon atom of pentagonal ring. This shift makes each ring have closer to 4''n''+2 π electrons, in keeping with the Hückel's pattern of aromatic stability. However, in the lowest quintet state, the central double bond is polarized with a partial negative charge on the carbon atom of heptagonal ring and a partial positive charge on the carbon atom of pentagonal ring due to Baird's rule. See also * Tropone * Biphenyl Biphenyl (also known as diphenyl, phenylbenzene, 1,1′-biphenyl, lemonene or BP) is an organic compound that forms colorless crystals. Particularly in older literature, compounds ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mesomer
In chemistry, resonance, also called mesomerism, is a way of describing bonding in certain molecules or polyatomic ions by the combination of several contributing structures (or ''forms'', also variously known as ''resonance structures'' or ''canonical structures'') into a resonance hybrid (or ''hybrid structure'') in valence bond theory. It has particular value for analyzing delocalized electrons where the bonding cannot be expressed by one single Lewis structure. Overview Under the framework of valence bond theory, resonance is an extension of the idea that the bonding in a chemical species can be described by a Lewis structure. For many chemical species, a single Lewis structure, consisting of atoms obeying the octet rule, possibly bearing formal charges, and connected by bonds of positive integer order, is sufficient for describing the chemical bonding and rationalizing experimentally determined molecular properties like bond lengths, angles, and dipole moment. However ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Benzannulation
In organic chemistry annulation (from the Latin ''anellus'' for "little ring"; occasionally annelation) is a chemical reaction in which a new ring is constructed on a molecule. : Examples are the Robinson annulation, Danheiser annulation and certain cycloadditions. Annular molecules are constructed from side-on condensed cyclic segments, for example helicenes and acenes. In transannulation a bicyclic molecule is created by intramolecular carbon-carbon bond formation in a large monocyclic ring. An example is the samarium(II) iodide induced ketone - alkene cyclization of ''5-methylenecyclooctanone'' which proceeds through a ketyl intermediate: : Benzannulation The term benzannulated compounds refers to derivatives of cyclic compounds (usually aromatic) which are fused to a benzene ring. Examples are listed in the table below: In contemporary chemical literature, the term benzannulation also means "construction of benzene rings from acyclic precursors". upright=1.4, Protonatio ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Triafulvalene
Triafulvalene or cyclopropenylidenecyclopropene is a fulvalene hydrocarbon with chemical formula C6H4, composed of two linked cyclopropene rings. Triafulvalene has never been isolated, since it can decompose via an isodesmic reaction. However, this molecule is of theoretical significance for theoretical organic chemists, and its structure, stability, and spectral properties are well-studied. See also * Calicene * Fulvalene * Sesquifulvalene Sesquifulvalene or Pentaheptafulvalene is a hydrocarbon in the fulvalene class with chemical formula C12H10. It is composed of linked cyclopentadiene and cycloheptatriene rings. Properties In the ground state, which is a singlet state, the cent ... References {{theoretical-chem-stub Fulvalenes Hypothetical chemical compounds Cyclopropenes ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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