2,7-Diphenyloxepin

McManus, Michael J.; Berchtold, Glenn A.; Boyd, Derek R.; Kennedy, Deirdre A.; Malone, John F.

doi:10.1021/jo00364a031

Cited by 14 publications

(7 citation statements)

References 1 publication

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“…29 However, 2,7-diphenyloxepin has been reported to take a boat conformation by X-ray structure analysis. 33 The theoretical bond distances in the boat C s structure are in qualitative accord with the values observed for the diphenyl derivative. The D 2h structure of 3 shows that the CN bond length of 1.334 Å is comparable to the experimental value of 1.338 Å in pyridine and that the CC bonds exhibit normal atomic distances in ordinary aromatic hydrocarbons.…”

Section: Location Of Energy Minimum and Transition Structuressupporting

confidence: 76%

“…The derivatives of 1-4 are known to exist as nonplanar conformations by X-ray structure analyses. [28][29][30][31][32][33][34][35]…”

Section: Introductionmentioning

confidence: 99%

“…With a view to obtaining the physical picture of such structural changes, we carry out an energy component analysis of the total energy and hence elucidate the nature of the pseudo-JT distortion from planarity. To address this question, we deal here with the representative heterocyclic systems with eight π electrons (Figure ) by means of the ab initio MCSCF method , with the 6-31G(d,p) basis sets: − azepine ( 1 ), − oxepin ( 2 ), ,− 1,5-diazocine ( 3 ), and 1,3,5,7-tetrazocine ( 4 ), the latter two being diaza and tetraaza derivatives of cyclooctatetraene, respectively. The derivatives of 1 − 4 are known to exist as nonplanar conformations by X-ray structure analyses. −

1 Molecular skeletons and numbering of atoms for 1 − 4 .…”

Section: Introductionmentioning

confidence: 99%

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Pseudo-Jahn−Teller Distortion from Planarity in Heterocyclic Seven- and Eight-Membered Ring Systems with Eight π Electrons

et al. 2003

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To elucidate the nature of a pseudo-Jahn-Teller (JT) distortion from planarity, ab initio MCSCF calculations with the 6-31G(d,p) basis sets were carried out in the ground states of seven-and eight-membered unsaturated heterocycles with eight π electrons. The monocyclic systems examined were found to show a variety of structural changes. Azepine and oxepin undergo the pseudo-JT distortions from a planar C 2V to a boat C s conformation. In 1,5-diazocine, the pseudo-JT distortion takes place in two stages, the initial step being from a symmetric planar D 2h to a skew C 2h structure and the subsequent step from the skew C 2h to a tub C 2 structure. The 1,3,5,7-tetrazocine molecule undergoes pseudo-JT distortions from a symmetric planar D 4h to skew C 4h and crown-like D 2d structures through the respective in-plane and out-of-plane nuclear deformations. Moreover, the C 4h and D 2d structures are distorted into the same tub-shaped S 4 conformation. An inspection of the energy components comprised in the total energy reveals that the stability of nonplanar structures arises from a lowering of the electron-nuclear attraction energy. The energy variation is accounted for in terms of an electrostatic interaction and the proximity among the nuclei and electron clouds owing to a folding of the molecular skeleton. It is shown that the theoretical structural characteristics for azepine, oxepin, 1,5-diazocine, and 1,3,5,7-tetrazocine are in good agreement with available experimental facts.

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Section: Location Of Energy Minimum and Transition Structuressupporting

confidence: 76%

“…The derivatives of 1-4 are known to exist as nonplanar conformations by X-ray structure analyses. [28][29][30][31][32][33][34][35]…”

Section: Introductionmentioning

confidence: 99%

1 Molecular skeletons and numbering of atoms for 1 − 4 .…”

Section: Introductionmentioning

confidence: 99%

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Pseudo-Jahn−Teller Distortion from Planarity in Heterocyclic Seven- and Eight-Membered Ring Systems with Eight π Electrons

et al. 2003

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“…Cyclic 8π‐electron molecules in their S 0 states normally adopt non‐planar structures that are non‐aromatic rather than antiaromatic. Cyclooctatetraene (COT) in S 0 adopts a tub‐shaped geometry, avoiding the angle strain at the planar D 4h symmetric structure, and also azepines, oxepines, and thiepines adopt puckered conformations . The resonance energies of the planar structures of azepine and oxepines obtained through extended Hückel MO theory and early Hartree‐Fock computations suggested antiaromatic character, later supported by NICS calculations .…”

Section: Introductionmentioning

confidence: 89%

“…Cyclooctatetraene (COT) in S 0 adopts a tub-shaped geometry, avoiding the angle strain at the planar D 4h symmetric structure, [12] and also azepines, oxepines, and thiepines adopt puckered conformations. [13][14][15][16][17][18][19] The resonance energies of the planar structures of azepine and oxepines obtained through extended Hückel MO theory and early Hartree-Fock computations suggested antiaromatic character, [20,21] later supported by NICS calculations. [14,22] However, the dibenz[b,f]annelated derivatives were found to have positive resonance energies associated with some aromatic character as their benzene rings keep their Hückel aromaticity in line with Glidewell-Lloyd's extension of Clar's rule.…”

Section: Introductionmentioning

confidence: 95%

Is Excited‐State Aromaticity a Driving Force for Planarization of Dibenzannelated 8π‐Electron Heterocycles?

et al. 2019

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Compounds with dibenzannelated heterocycles with eight π‐electrons are found in a range of applications. These molecules often adopt a bent structure in the ground state (S0) but can become planar in the first excited states (S1 and T1) because of the cyclically conjugated 4nπ central ring, which fulfils the requirements for excited state aromaticity. We report on a quantum chemical investigation of the aromatic character in the S1 and T1 states of dibenzannelated seven‐ and six‐membered heterocycles with one, two, or three heteroatoms in the 8π‐electron ring. These states could have ππ* or nπ* character. We find that compounds with one or two heteroatoms in the central ring have ππ* states as their S1 and T1 states. They are to a significant degree influenced by excited state aromaticity, and their optimal structures are planar or nearly planar. Among the heteroatoms, nitrogen provides for the strongest excited state aromaticity whereas oxygen provides for the weakest, following the established trend of the S0 state. Yet, dibenzannelated seven‐membered‐ring compounds with N=N bonds have non‐aromatic nπ* states with strongly puckered structures as their S1 and T1 states.

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Tautomeric Equilibria and Rearrangements Involving Phenols

Koblik¹

2009

Patai's Chemistry of Functional Groups

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Introduction Tautomerism in Phenols Rearrangements of Phenols Rearrangements of O ‐Substituted Phenol Derivatives Rearrangements of Functionalized Arenes Rearrangements of Non‐Aromatic Carbocycles Rearrangements of Heterocyclic Compounds

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2,7-Diphenyloxepin

Cited by 14 publications

References 1 publication

Pseudo-Jahn−Teller Distortion from Planarity in Heterocyclic Seven- and Eight-Membered Ring Systems with Eight π Electrons

Pseudo-Jahn−Teller Distortion from Planarity in Heterocyclic Seven- and Eight-Membered Ring Systems with Eight π Electrons

Is Excited‐State Aromaticity a Driving Force for Planarization of Dibenzannelated 8π‐Electron Heterocycles?

Tautomeric Equilibria and Rearrangements Involving Phenols

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