Perfluorotetracyclobutacyclo-octatetraene; a planar eight-membered ring system; X-ray crystal structure

Einstein, Frederick W. B.; Willis, Anthony C.; Cullen, William R.; Soulen, Robert L.

doi:10.1039/c39810000526

Cited by 49 publications

(33 citation statements)

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“…C-1, C-4, C-5, C-8), 49.75 (C-11, C-12), 113.33 (C-9, C-10), 145.20 (C-4a, C-8a, C-9a, C-10a); IR (KBr): n Ä (20 mL) and washed with NaOH (1m, 2 Â 10 mL) and water (10 mL). The solution was dried over Na 2 SO 4 …”

Section: Methodsmentioning

confidence: 99%

“…[2,3] Hitherto, only two derivatives are known, which according to crystal structure analyses contain planar eight-membered rings with p bonds tending toward localization. [4] Recently, the parent planar COT has been observed by means of transition-state spectroscopy. Accordingly, the singlet lies well below the triplet D 8h COT in agreement with ab initio predictions that COT violates Hunds rule.…”

Section: Introductionmentioning

confidence: 99%

“…The Diels ± Alder adduct 16, separated from its isomer 17 by liquid chromatography, is thermally labile and undergoes an intramolecular retro-Diels ± Alder reaction to give 17 on heating at 53 8C (half-life: 2.5 h). Attempts to catalyze the cycloaddition of DCA to 15 by means of a Lewis acid, such as AlCl 3 or TiCl 4 , failed. The reaction of DCA with 15 in the presence of AlCl 3 or TiCl 4 leads to products of higher molecular weight that could not be identified.…”

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confidence: 98%

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Pressure-Induced Cycloadditions of Dicyanoacetylene to Strained Arenes: The Formation of Cyclooctatetraene, 9,10-Dihydronaphthalene, and Azulene Derivatives; A Degenerate [1,5] Sigmatropic Shift—Comparison between Theory and Experiment

et al. 1999

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Abstract:The reaction of dicyanoacetylene (DCA) with the partially hydrogenated dimethano-bridged anthracene and pentacene derivatives 3 and 18 lead to the (1:1) Diels ± Alder adducts 5 and 19, respectively, and to the 9,10-dihydronaphthalene derivatives 6 and 21, respectively. These compounds are intensely colored, most likely due to a charge-transfer absorption. Photolysis of the (1:1) adducts 5 and 19 produces the corresponding cyclooctatetraene derivatives 7 and 8, which are not planar despite the torsional constraints caused by the fusion of the eight-membered ring to norbornane and norbornene units. The mechanisms of formation of the dihydronaphthalene derivatives 6 and 21 were elucidated by the use of high pressure; this allowed the (2:1) adducts 11 and 20 to be detected as intermediates in the reaction of DCA with 5 or 19 to give 6 and 21, respectively. A degenerate rearrangement consisting formally of a [1,5] The finding that the irreversible rearrangement of 6 accompanied by the elimination of HCN to give the azulene derivative 14 proceeds only on heating of 6 to 80 8C in a polar solvent is good evidence for a polar mechanism in this case.

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Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

mentioning

confidence: 98%

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Pressure-Induced Cycloadditions of Dicyanoacetylene to Strained Arenes: The Formation of Cyclooctatetraene, 9,10-Dihydronaphthalene, and Azulene Derivatives; A Degenerate [1,5] Sigmatropic Shift—Comparison between Theory and Experiment

et al. 1999

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“…This deviation from near D 3h symmetry we ascribe to a steric hindrance between the bulky pentamethyl (26) and tetramethylethylcyclopentadienyl (27) ligands of the cobalt series. The fact that such a distortion is missing in 32, the rhodium congener of 26, we attribute to the longer distances between rhodium and both ring centers (1.83 and 1.90 in 32) as compared to cobalt and the ring centers (1.71 and 1.72 in 26).…”

Section: Structural Investigationsmentioning

confidence: 92%

Synthesis, Properties and Formation of (RCp)Co‐ and (RCp)Rh‐Stabilized[4.8]₃Cyclacene Derivatives

Kornmayer¹,

Hellbach²,

Röminger³

et al. 2009

Chemistry A European J

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Metal-stabilized belts: A torus, 3, consisting of three four- and three eight-membered conjugated rings and stabilized by (RCp)Co- and (RCp)Rh- units, was generated by irradiation of [(RCp)Co(CO)(2)] and [(RCp)Rh(C(2)H(4))(2)], respectively, and 1.Eleven metal stabilized [4.8](3)cyclacene derivatives were synthesized. The substances were prepared in one-pot reactions by irradiation of a solution of 5,6,11,12-tetradehydro-dibenzo[a,e]cyclooctatetraene and the corresponding cobalt reagents or rhodium compounds. The resulting cyclacene derivatives reveal D(3h) symmetry in solution. In the solid state the hoop shaped systems crystallize in layers, which are intercalated with solvent layers. To unravel the mechanism of the one-pot reaction we isolated an intermediate, which shows almost planar cyclooctatetraene rings.

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“…Thus, 30 represents a unique naphthalene, in which one six-membered ring is aromatic and the other is olefinic. 48 In fact, the molecular structure of 29, determined by X-ray crystallography, shows that the central eight-membered ring is entirely planar (Fig. 18).…”

mentioning

confidence: 99%

Studies on Two- and Three-Dimensional π-Conjugated Systems with Unique Structures and Properties

Komatsu¹

2007

Bulletin of the Chemical Society of Japan

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A series of two-dimensional, cyclic -conjugated systems with the six-membered to eight-membered rings as well as polycyclic aromatic compounds and sulfur-containing compounds, which were fully surrounded by rigid bicyclicframeworks, were synthesized and their structures and properties elucidated. This structural modification is characteristic to cause an elevation of the HOMO levels of neutral -systems and to stabilize remarkably the corresponding cationic systems by both thermodynamic and kinetic effects. In contrast to annelation with a strain-free bicyclic system, such as bicyclo[2.2.2]octene, annelation with a more strained system, such as bicyclo[2.1.1]hexene, brings about a large bond fixation effect upon the cyclic -system. Thus, -conjugated systems with quite unusual electronic structures can be prepared by using combination of these structural modifications. As another example of unusual structure, a novel three-dimensional -conjugated system, i.e., fullerene encapsulating molecular hydrogen, was synthesized from empty fullerene using organic reactions. This is taken as an entirely new approach to the endohedral fullerenes, of which the production has so far relied only on physical methods.

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Perfluorotetracyclobutacyclo-octatetraene; a planar eight-membered ring system; X-ray crystal structure

Cited by 49 publications

References 0 publications

Pressure-Induced Cycloadditions of Dicyanoacetylene to Strained Arenes: The Formation of Cyclooctatetraene, 9,10-Dihydronaphthalene, and Azulene Derivatives; A Degenerate [1,5] Sigmatropic Shift—Comparison between Theory and Experiment

Pressure-Induced Cycloadditions of Dicyanoacetylene to Strained Arenes: The Formation of Cyclooctatetraene, 9,10-Dihydronaphthalene, and Azulene Derivatives; A Degenerate [1,5] Sigmatropic Shift—Comparison between Theory and Experiment

Synthesis, Properties and Formation of (RCp)Co‐ and (RCp)Rh‐Stabilized[4.8]₃Cyclacene Derivatives

Studies on Two- and Three-Dimensional π-Conjugated Systems with Unique Structures and Properties

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Perfluorotetracyclobutacyclo-octatetraene; a planar eight-membered ring system; X-ray crystal structure

Cited by 49 publications

References 0 publications

Pressure-Induced Cycloadditions of Dicyanoacetylene to Strained Arenes: The Formation of Cyclooctatetraene, 9,10-Dihydronaphthalene, and Azulene Derivatives; A Degenerate [1,5] Sigmatropic Shift—Comparison between Theory and Experiment

Pressure-Induced Cycloadditions of Dicyanoacetylene to Strained Arenes: The Formation of Cyclooctatetraene, 9,10-Dihydronaphthalene, and Azulene Derivatives; A Degenerate [1,5] Sigmatropic Shift—Comparison between Theory and Experiment

Synthesis, Properties and Formation of (RCp)Co‐ and (RCp)Rh‐Stabilized[4.8]3Cyclacene Derivatives

Studies on Two- and Three-Dimensional π-Conjugated Systems with Unique Structures and Properties

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Synthesis, Properties and Formation of (RCp)Co‐ and (RCp)Rh‐Stabilized[4.8]₃Cyclacene Derivatives