chembox verifiedrevid 444042371 Name Cyclooctatetraene ImageFileL1 Cyclooctatetraen.svg ImageSizeL1 100px ImageFile2 Cyclooctatetraene 3d.png ImageSize2 150px ImageFileR1 Cyclooctatetraene profile 3D balls.png ImageSizeR1 120px IUPACName 1,3,5,7 cyclooctatetraene OtherNames COT, 8 annulene Section1 Chembox Identifiers SMILES C1 C C C C C C C1 ChemSpiderID Ref chemspidercite correct chemspider ChemSpiderID 553448 CASNo 629 20 9 CASNo Ref cascite correct CAS RTECS CY1400000 InChI 1 C8H8 c1 2 4 6 8 ... Cyclooctatetraene COT is an saturation chemistry unsaturated Derivative chemistry derivative ... controversy. Unlike benzene, C sub 6 sub H sub 6 sub , however, cyclooctatetraene, C sub 8 sub H sub ... reaction s, much as alkane s do, not additions. History 1,3,5,7 Cyclooctatetraene was initially ... Willstaetter Synthesis COT.svg 450px Willst tter s synthesis of cyclooctatetraene 1905 Willst tter ... chemists were untroubled by the reduction of his cyclooctatetraene to cyclooctane a reaction ... File All Z Cyclooctatetraene 3D skeletal formula.svg left 180px thumb Cyclooctatetraene in its ... from H. S. Kaufman demonstrated cyclooctatetraene to adopt several Cyclohexane conformation ... single and double C C bonds. In its normal state, cyclooctatetraene is non planar and adopts a tub conformation ... spectra of 1,3,5,7 cyclooctatetraene and 1,5 cyclooctadiene author Thomas, P. M. Weber, A. journal ... framework gives relatively low yields. Reppe s synthesis of cyclooctatetraene, which ... upright 1.5 Reppe s synthesis of cyclooctatetraene COT can also be prepared by photolysis of barrelene ... occurrence Cyclooctatetraene has been isolated from certain fungi. ref Stinson, M. Ezra, D. Hess ... been synthesized via the ring opening polymerization of cyclooctatetraene. ref Two Undergraduate Experiments ... and aromatic with a Huckel rule Huckel electron count of 10. Cyclooctatetraene forms Organometallic ... generated title ref See also Cyclobutadiene Semibullvalene and barrelene , structural isomer s of cyclooctatetraene ... more details
The molecular formula C sub 8 sub H sub 8 sub may refer to Barrelene Benzocyclobutene Cubane Cuneane Cyclooctatetraene Bullvalene Semibullvalene Semibullvalene Styrene MolFormDisambig el C8H8 fr C8H8 it C8H8 nl C8H8 sr C8H8 ... more details
chembox verifiedrevid 413769870 Reference ref http www.sigmaaldrich.com catalog search ProductDetail ALDRICH 379328 Tetraphenylene at Sigma Aldrich ref Name Tetraphenylene ImageFile Tetraphenylene.svg ImageSize 150px ImageName Skeletal formula ImageFile1 Tetraphenylene 3D spacefill.png ImageSize1 200px ImageName1 Space filling model IUPACName Tetrabenzocyclooctatetraene Section1 Chembox Identifiers CASNo Ref cascite correct ?? CASNo 212 74 8 PubChem 2724868 SMILES C1 CC C2C C1 C3 CC CC C3 C4 CC CC C4C5 CC CC C25 Section2 Chembox Properties Formula C sub 24 sub H sub 16 sub MolarMass 304.39 g mol MeltingPt 232 235 C BoilingPt 577.6 760mmHg Density 1.19g cm3 FlashPt 297.9 C Tetraphenylene is an organic compound , solid at room temperature, with the chemical formula C sub 24 sub H sub 16 sub . It is a member of the Saturation chemistry unsaturated polycyclic hydrocarbon s class of compounds. See also Cyclooctatetraene References references PAHs hydrocarbon stub Category Polycyclic aromatic hydrocarbons fa fr T traph nyl ne nl Tetrafenyleen ja th ... more details
MEDIATED HIGHER ORDER CYCLOADDITION collvol 10 collvolpages 1 year 2004 prep CV10P0001 ref Cyclooctatetraene ... s. ref cite journal author Tomi Nath Das, K. Indira Priyadarsini title Triplet of Cyclooctatetraene ..., H. Samelson, and A. Lempicki title Long Pulse Laser Emission From Rhodamine 6G Using Cyclooctatetraene ... ref See also Cyclopentadiene Cyclooctatetraene Benzene References Reflist Annulenes External links Category ... more details
Chembox Watchedfields changed verifiedrevid 416385697 ImageFile Cyclobutadienyl iron tricarbonyl from xtal 3D balls.png ImageSize ImageAlt IUPACName PIN OtherNames Section1 Chembox Identifiers CASNo Ref cascite correct ?? CASNo PubChem SMILES Section2 Chembox Properties Formula C sub 4 sub H sub 4 sub Fe CO sub 3 sub Appearance Density MeltingPt BoilingPt Solubility Section3 Chembox Hazards MainHazards FlashPt Autoignition Cyclobutadieneiron tricarbonyl or C sub 4 sub H sub 4 sub Fe CO sub 3 sub is an organometallic complex of cyclobutadiene and an iron metal carbonyl . The chemical compound is used in organic chemistry as a precursor for cyclobutadiene. Preparation It was first prepared in 1965 by Rowland Pettit starting from cyclooctatetraene ref Cyclobutadiene and Benzocyclobutadiene Iron Tricarbonyl Complexes G. F. Emerson, L. Watts, R. Pettit J. Am. Chem. Soc. 1965 87 1 131 133. http pubs.acs.org cgi bin abstract.cgi jacsat 1965 87 i01 f pdf f ja01079a032.pdf First Page ref ref Cis dichlorocyclobutene , Organic Syntheses , Coll. Vol. 6, p.422 1988 Vol. 50, p.36 1970 http www.orgsyn.org orgsyn prep.asp?prep cv6p0422 Article . ref ref Iron, tricarbonyl 4 1,3 cyclobutadiene R. Pettit and J. Henery Organic Syntheses , Coll. Vol. 6, p.310 1988 Vol. 50, p.21 1970 http www.orgsyn.org orgsyn orgsyn prepContent.asp?prep cv6p0310 Link ref Image CyclobutadieneirontricarbonylSynthesis.png 600px Cyclobutadieneiron tricarbonyl Synthesis Cyclooctatetraene is chlorinated to the 4.2.0 bicyclic compound which reacts further with the alkyne dimethyl acetylenedicarboxylate in a Diels Alder reaction followed by a reverse DA reaction by pyrolysis at 200 C releasing cis dichlorocyclobutene. This compound reacts with di iron nonacarbonyl obtained from photolysis of iron pentacarbonyl to Cyclobutadieneiron tricarbonyl. Properties Cyclobutadieneiron tricarbonyl displays aromaticity as evidenced by some of its reactions which can be classified as electrophilic aromatic substitution ref ... more details
Frost orbs.png thumb right 220px The Jahn Teller effect forces the radical anion of cyclooctatetraene ... pubs.acs.org doi pdf 10.1021 ed069p819 DOI 10.1021 ed069p819 ref and cyclooctatetraene . ref cite journal author Frank Gerrit Kl rner title About the Antiaromaticity of Planar Cyclooctatetraene year 2001 ... J. Bearpark title Observation of Both Jahn Teller Distorted Forms b1g and b2g of the Cyclooctatetraene ... more details
Wiktionary cot TOCright Cot , COT or CoT , may refer to Beds A camp bed , a simple, temporary and portable bed A baby s infant bed See cot side for beds with raised sides Transportation Car of Tomorrow , a new car design by NASCAR Cottingley railway station , National Rail station code COT RAF Cottesmore Flying Training Unit, United Kingdom ICAO airline designator Math and Science Cot analysis , a biochemical technique that measures how much repetitive DNA is in a genome Cotangent , trigonometric function cot Cotyledon , a significant part of the embryo within the seed of a plant Cyclooctatetraene , an unsaturated hydrocarbon, and cyclooctatetraenyl, a functional group in chemistry derived from it, both abbreviated COT People Comando de Opera es T ticas , a Brazilian counter terrorism force Pierre Auguste Cot 1837&ndash 1883 , French painter of the Academic Classicism school Acronyms Time in Colombia Colombian Time , the time offset used in Colombia corresponds yearlong to UTC 5 Commitments of Traders COT Report, issued weekly by the Commodity Futures Trading Commission summarizing market activity Crossroads of Twilight , is the tenth book of The Wheel of Time fantasy series written by American author Robert Jordan Change Over Time , an academic journal published by the University of Pennsylvania Press Committee on Toxicity of Chemicals in Food, Consumer Products and the Environment, a UK official body Court of the Table of Insurance sales persons who achieve three times the requirements for membership of the Million Dollar Round Table Other Malbec grapes, known in the Loire Valley as C t A finger cot , a hygienic cover for a single finger See also Khat , a drug disambiguation bg de Cot es COT eo COT fr Cot it COT nl Cot ja COT ro Cot dezambiguizare zh COT ... more details
In organic chemistry, two molecules are valence isomers when they are constitutional isomer s that can interconvert through pericyclic reaction s. ref GoldBookRef file V06590 year 1994 title Valence isomer ref ref Rearrangements and interconversions of compounds of the formula CH n Lawrence T. Scott, Maitland. Jones Chem. Rev. , 1972, 72 2 , pp 181 202 DOI 10.1021 cr60276a004 ref Benzene For example, Dewar benzene transforms spontaneously into its valence isomer benzene . The compounds both can be described as CH sub 6 sub but the arrangement of the six carbon hydrogen blocks is different. Besides benzene and Dewar benzene, prismane , benzvalene and bicyclopropenyl are also valence isomers of the CH sub 6 sub family. Topologically, more arrangements in this family are possible, though they have not been attested to in chemistry. The ring strain on angles or lengths of bonding prohibit their actual formation. gallery caption The valence isomers of benzene perrow 5 Image Benzene 2D flat.png Benzene Image Dewarbenzene structure.svg Dewar benzene Image Prisman2.svg Prismane Image Benzvalene.png Benzvalene Image Bicycloprop 2 enyl.svg Bicyclopropenyl gallery Cyclooctatetraene The valence isomers are not restricted to isomers of benzene. Valence isomers are also seen in the series CH sub 8 sub . Due to the larger number of units, the number of possible valence isomers is also greater and at least 21 gallery caption Valence isomers of cyclooctatetraene perrow 5 Image Cyclooctatetraene.png Cyclooctatetraene COT Image Barrelene structure.png Barrelene Image Cuban.svg Cubane Image Cuneane.png Cuneane Image Semibullvalene.svg Semibullvalene Image Bicyclo420octa247triene.svg Bicyclo 4.2.0 octa 2,4,7 triene . Tautomer with COT by thermal 6e process or photochemical 4e process ref cite journal last1 Huisgen first1 R. last2 Mietzsch first2 F. title The Valence Tautomerism of Cyclooctatetraene journal Angewandte Chemie International Edition in English volume 3 pages 83 year 1964 do ... more details
The cyclooctatetraenide dianion is an aromatic organic chemistry organic anion with the structure C sub 8 sub H sub 8 sub sup 2 sup . It is planar and aromatic, like the cyclopentadienide anion, and, like cyclopentadienide, easily forms compounds with metals. Image Cyclooctatetraenide 3D ball.png thumb right 200px Ball and stick model of COT sup 2 sup Compounds The salt potassium cyclooctatetraenide is easily formed by the reaction of cyclooctatetraene with potassium metal. It has the structure K sub 2 sub C sub 8 sub H sub 8 sub , or K sub 2 sub COT . Cyclooctatetraenic acid is a hypothetical acid with the structure H sub 2 sub C sub 8 sub H sub 8 sub , or H sub 2 sub COT . Image Uranocene 3D vdW.png thumb right Uranocene , a sandwich compound containing two COT sup 2 sup rings. Several sandwich compound s involving the cyclooctatetraenide anion are known, the most notable of which are the actinocene s, such as uranocene , U C sub 8 sub H sub 8 sub sub 2 sub or U COT sub 2 sub , thorocene , Th C sub 8 sub H sub 8 sub sub 2 sub or Th COT sub 2 sub , and plutonocene , Pu C sub 8 sub H sub 8 sub sub 2 sub ferricene not to be confused with ferrocene , Fe C sub 8 sub H sub 8 sub sub 2 sub , is also known. Since the actinides can also exist in the III oxidation stade, they can also exist in the form where A is any actinide AC sub 5 sub H sub 5 sub C sub 8 sub H sub 8 sub , or A Cp COT , as the cyclopentadienide cyclooctatetraenide. An example of this is UC sub 5 sub H sub 5 sub C sub 8 sub H sub 8 sub , or uranium cyclopentadienide cyclooctatetraenide. Category Organic chemistry ... more details
Chembox ImageFile Cycloocta 1,3,6 triene.svg ImageFile Ref chemboximage correct ?? ImageSize 100 ImageName Skeletal formula of cycloocta 1,3,6 triene 1 Z ,3 Z ,6 Z 1,3,6 triene SystematicName Cycloocta 1,3,6 triene ref Cite web title CID 34696 Compound Summary url http pubchem.ncbi.nlm.nih.gov summary summary.cgi?cid 34696 work PubChem Compound publisher National Center for Biotechnology Information accessdate 13 October 2011 location USA date 27 March 2005 at Identification and Related Records ref Section1 Chembox Identifiers CASNo 3725 30 2 CASNo Comment small 1 Z ,3 Z ,6 Z 1,3,6 triene small CASNo Ref cascite correct CAS PubChem 34696 PubChem Ref Pubchemcite correct Pubchem PubChem1 5367250 PubChem1 Ref Pubchemcite correct Pubchem PubChem1 Comment small 1 Z ,3 Z ,6 Z 1,3,6 triene small ChemSpiderID 4518805 ChemSpiderID Ref chemspidercite correct chemspider ChemSpiderID Comment small 1 Z ,3 Z ,6 Z 1,3,6 triene small ChEBI 37892 ChEBI Ref ebicite correct EBI Beilstein 1848165 Gmelin 260126 SMILES C1C CCC CC C1 StdInChI 1S C8H10 c1 2 4 6 8 7 5 3 1 h1 4,7 8H,5 6H2 b3 1 ,4 2 ,8 7 StdInChIKey LHNSMWDERKGLJK DKPWQKSPSA N Section2 Chembox Properties C 8 H 10 ExactMass 106.078250320 g mol sup 1 sup MeltingPtK 214 BoilingPtK 341 Boiling notes at 8.0 kPa Cycloocta 1,3,6 triene is an organic compound organic chemical compound related to cyclooctatetraene . It is an example of a cycloalkene which exhibits geometric isomerism. References Reflist Category Cycloalkenes Hydrocarbon stub ... more details
, E. M. Burgess title Photochemical reactions. X. Experiments with 1,3,5 cyclooctatrien 7 one, and cyclooctatetraene ... from Burgess s Ph.D. Dissertation. Image EMB Cyclooctatetraene oxide.svg Cyclooctatetraene epoxide ... more details
File Benzene bonds.svg right thumb Benzene 6 annulene . File 14 Annulene.svg right thumb Cyclotetradecaheptaene 14 annulene . File 18 Annulene.svg right thumb Cyclooctadecanonaene 18 annulene . Annulenes are completely Conjugated system conjugated Cyclic compound monocyclic hydrocarbon s. They have the general formula C sub n sub H sub n sub when n is an even number or C sub n sub H sub n 1 sub when n is an odd number . The IUPAC nomenclature IUPAC naming conventions are that annulenes with 7 or more carbon atoms are named as n annulene, where n is the number of carbon atom s in their ring, ref GoldBookRef title annulene file A00368 ref though sometimes the smaller annulenes are referred to using the same notation, and benzene is sometimes referred to simply as annulene. ref Ege, S. 1994 Organic Chemistry Structure and Reactivity 3rd ed. D.C. Heath and Company ref ref Dublin City University http www.dcu.ie chemist pratt annulene annulene.htm Annulenes ref The first three annulenes are cyclobutadiene , benzene , and cyclooctatetraene 8 annulene . Some annulenes, namely cyclobutadiene, cyclodecapentaene or 10 annulene, cyclododecahexaene or 12 annulene and cyclotetradecaheptaene 14 annulene , are unstable, with cyclobutadiene extremely so. Annulenes may be aromatic benzene, 14 annulene, cyclooctadecanonaene or 18 annulene , non aromatic 10 annulene , or anti aromatic cyclobutadiene . Only cyclobutadiene and benzene are fully Plane geometry planar , though 14 and 18 annulene with all trans double bonds placing the hydrogens inside the ring can achieve the planar conformation needed for aromaticity, with 14 and 18 annulene following H ckel s rule with 4n 2 Pi bond electrons . 14 annulene does exhibit some ring strain due to steric hindrance . Many of the larger annulenes, 18 annuelene for example, are large enough to minimize the van der Waals strain of internal hydrogens and thermodynamically qualify as aromatic. However, none of the larger annulenes are as stable as ... more details
chembox verifiedrevid 381670614 ImageFile Pentalene.svg ImageSize 180px ImageFile1 Pentalene 3D balls.png ImageSize1 180 IUPACName Pentalene OtherNames Section1 Chembox Identifiers CASNo Ref cascite correct ?? CASNo 250 25 9 PubChem 5460726 SMILES c1cc2cccc2c1 InChI 1 C8H6 c1 3 7 5 2 6 8 7 4 1 h1 6H ChEBI Ref ebicite correct EBI ChEBI 33074 Section2 Chembox Properties Formula C sub 8 sub H sub 6 sub MolarMass 102.13 g mol Appearance Density MeltingPt BoilingPt Solubility Section7 Chembox Hazards MainHazards FlashPt Autoignition Pentalene is a polycyclic hydrocarbon composed of two fused cyclopentadiene rings. It has chemical formula C sub 8 sub H sub 6 sub . It is antiaromaticity antiaromatic , because it has H ckel s rule 4n pi electron s. For this reason it Dimer chemistry dimer izes even at temperatures as low as 100 C. ref Carey, Francis A. Sundberg, Richard J. 1984 . Advanced Organic Chemistry Part A Structure and Mechanisms 2nd ed. . New York N.Y. Plenum Press. ISBN 0 306 41198 9. ref ref cite journal author Bally T., Chai S., Neuenschwander M., Zhu Z. date 1997 title Pentalene Formation, Electronic, and Vibrational Structure journal J. Am. Chem. Soc. volume 119 issue 8 pages 1869 1875 7 doi 10.1021 ja963439t url http www chem.unifr.ch tb bally pdf pentalene.pdf format reprint ref Dilithium pentalenide was isolated 1962 long before pentalene itself 1997 . ref The Pentalenyl Dianion Thomas J. Katz, Michael Rosenberger J. Am. Chem. Soc. 1962 84 5 865 866. DOI 10.1021 ja00864a038 ref It is prepared from reaction of dihydropentalene pyrolysis of an isomer of dicyclopentadiene with N Butyllithium n butyllithium in solution and forms a stable salt. In accordance with its structure proton NMR shows 2 signals in a 2 to 1 ratio. The addition of two electrons removes the antiaromaticity it becomes a planar 10 pi aromatic species and is thus a bicyclic analogue of the cyclooctatetraene COT dianion C sub 8 sub H sub 8 sub sup 2 sup . Image Pentalenide.svg 500px Synthesis ... more details
in 1963 by G. Schr der by photolysis of a dimer of cyclooctatetraene with expulsion of benzene ... C the ethylated semibullvalene isomerisation isomerises to the cyclooctatetraene derivative. Image ... more details
to cyclooctatetraene , which is one of the most important applications of Template effect template ... provided an unusual route to benzene and especially to cyclooctatetraene , which was difficult to prepare ... more details
of alkyne oligomerization is the Reppe synthesis for example in the synthesis of cyclooctatetraene File Reppe Synthesis COT.svg frameless upright 1.5 Reppe s synthesis of cyclooctatetraene ... more details
See also List of UN Numbers UN 2301 to UN 2400 class wikitable width 140px UN Number Class Proper Shipping Name UN 2301 3 2 Methylfuran UN 2302 3 5 Methylhexan 2 one UN 2303 3 Isopropenylbenzene UN 2304 4.1 Naphthalene , molten UN 2305 8 Nitrobenzenesulfonic acid UN 2306 6.1 Nitrobenzotrifluoride s UN 2307 6.1 3 Nitro 4 chlorobenzotrifluoride UN 2308 8 Nitrosylsulfuric acid UN 2309 3 Octadiene UN 2310 3 Pentane 2,4 dione UN 2311 6.1 Phenetidine s UN 2312 6.1 Phenol , molten UN 2313 3 Picoline s UN 2315 9 Polychlorinated biphenyl s, liquid or solid UN 2316 6.1 Sodium cuprocyanide , solid UN 2317 6.1 Sodium cuprocyanide, solution UN 2318 4.2 Sodium hydrosulfide , with less than 25 percent water of crystallization UN 2319 3 Terpene hydrocarbon s, n.o.s. UN 2320 8 Tetraethylenepentamine UN 2321 6.1 Trichlorbenzene s, liquid UN 2322 6.1 Trichlorobutene UN 2323 3 Triethyl phosphite UN 2324 3 Triisobutylene UN 2325 3 1,3,5 Trimethylbenzene UN 2326 8 Trimethylcyclohexylamine UN 2327 8 Trimethylhexamethylenediamines UN 2328 6.1 Trimethylhexamethylene diisocyanate UN 2329 3 Trimethyl phosphite UN 2330 3 Undecane UN 2331 8 Zinc chloride , anhydrous UN 2332 3 Acetaldehyde oxime UN 2333 3 Allyl acetate UN 2334 6.1 Allylamine UN 2335 3 Allyl ethyl ether UN 2336 3 Allyl formate UN 2337 6.1 Phenyl mercaptan UN 2338 3 Benzotrifluoride UN 2339 3 2 Bromobutane UN 2340 3 2 Bromoethyl ethyl ether UN 2341 3 1 Bromo 3 methylbutane UN 2342 3 Bromomethylpropane s UN 2343 3 2 Bromopentane UN 2344 3 n Propyl bromide Bromopropanes or 2 Bromopropane s UN 2345 3 3 Bromopropyne UN 2346 3 Butanedione UN 2347 3 Butyl mercaptan s UN 2348 3 Butyl acrylate s, inhibited UN 2350 3 Butyl methyl ether UN 2351 3 Butyl nitrite s UN 2352 3 Butyl vinyl ether , inhibited UN 2353 3 Butyryl chloride UN 2354 3 Chloromethyl ethyl ether UN 2356 3 2 Chloropropane UN 2357 8 Cyclohexylamine UN 2358 3 Cyclooctatetraene UN 2359 3 Diallylamine UN 2360 3 Diallylether UN 2361 3 Diisobutylamine UN 2362 3 1,1 Dichloroethane ... more details
chembox verifiedrevid 426984115 ImageFileL1 Uranocene 2D skeletal.png ImageFileR1 Uranocene 2D dimensions.png ImageFileL2 Uranocene 3D vdW.png ImageFileR2 Uranocene 3D balls.png ImageSize IUPACName bis sup 8 sup cyclooctatetraenyl uranium IV OtherNames uranium cyclooctatetraenyl, U COT sub 2 sub Section1 Chembox Identifiers CASNo Ref cascite correct ?? CASNo 11079 26 8 PubChem 139204 SMILES U . CH 1 CH CH CH CH CH CH CH 1. CH 1 CH CH CH CH CH CH CH 1 Section2 Chembox Properties Formula C sub 16 sub H sub 16 sub U MolarMass 446.33 g mol Appearance green crystals ref name synth Density MeltingPt BoilingPt Solubility Section3 Chembox Hazards MainHazards ignites in air FlashPt Autoignition Uranocene U C sub 8 sub H sub 8 sub sub 2 sub is the most notable cyclooctatetraene cyclooctatetraenide of the f block f block elements and one of the first Organouranium chemistry organouranium compounds to be synthesized. Uranocene is a member of the actinocene s, a group of metallocene s incorporating Chemical element elements from the actinide series. It is the most studied bis 8 annulene metal system. Synthesis Uranocene was first prepared by the reaction of uranium tetrachloride and dipotassium cyclooctatetraene cyclooctatetraenide , viz. 2 K C sub 8 sub H sub 8 sub K sub 2 sub C sub 8 sub H sub 8 sub 2 K sub 2 sub C sub 8 sub H sub 8 sub UCl sub 4 sub U C sub 8 sub H sub 8 sub sub 2 sub 4 KCl. ref name synth Structure and chemical properties Uranocene is pyrophoricity pyrophoric , and stable to hydrolysis . Considering the molecule to be U sup 4 sup C sub 8 sub H sub 8 sub sup 2 sup sub 2 sub , the hapticity sup 8 sup Cyclooctatetraene Cyclooctatetraenide dianion cyclooctatetraenide groups are planar, as expected for a ring containing 10 Conjugated system electrons , and are mutually parallel, forming a Sandwich compound sandwich containing the uranium atom. In the solid state, the rings are eclipsed, conferring D sub 8h sub symmetry on the uranocene molecule. In solution ... more details
expert subject 1 Chemistry date October 2011 Image Antiaromats2.png 300px right Antiaromatic compounds Antiaromatic molecule s are Cyclic compound cyclic systems containing alternating single and double bond s, where the pi electron energy of antiaromatic compounds is higher than that of its open chain counterpart. Therefore antiaromatic compounds are unstable and highly reactive often antiaromatic compounds distort themselves out of planarity to resolve this instability. Antiaromatic compounds usually fail H ckel s rule of aromatic ity. The basic reason why anti aromatic compounds are so unstable is explained by the molecular orbital theory. According to this theory when anti aromatic compounds are formed then always 2 electrons remain in the non bonding orbitals. Now as non bonding molecular orbitals are unstable compared to atomic pi orbitals hence these compounds are highly unstable. This is also one of the major differences between aromatic and anti aromatic compounds that in the formation of aromatic compounds all the electrons go only in the bonding molecular orbitals and thus imparting a lot of stability to the compound. Examples of antiaromatic systems are cyclobutadiene A , the cyclopentadienyl cation B and the cyclopropenyl anion C . Cyclooctatetraene is a 4n system but neither aromatic or antiaromatic because the molecule escapes a planar geometry. By adding or removing an electron pair via a redox reaction, a system can become aromatic and therefore more stable than the original non or anti aromatic compound, for instance the cyclooctatetraenide dianion . The IUPAC criteria for antiaromaticity are as follows ref Compendium of Chemical Terminology , http goldbook.iupac.org A00382.html antiaromatic compounds , accessed 1 Feb 2007. ref The molecule must have 4 n electrons where n is any integer. The molecule must be cyclic. The molecule must have a conjugated pi electron system. The molecule must be planar. However, most chemists agree on the definitio ... more details
thumb 250px Benzene orbitals File All Z Cyclooctatetraene 3D skeletal formula.svg thumb 200px Cyclooctatetraene . Adjacent double bonds are not coplanar. Cyclic compound s can be partly or completely .... Cyclooctatetraene , for example, possesses alternating single and double bonds. The molecule ... more details
Article doi 10.1021 ja808524y ref and Ar Sn sub 2 sub Cyclooctatetraene COT . Double and multimetallic ... 10.1002 anie.198609281 ref , Ni sub 2 sub Cyclooctatetraene COT sub 2 sub ref cite journal author ... more details
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