Dications of Tetrabenzofulvalenes. Paratropicity and .sigma. Donation in Perpendicular Antiaromatic Systems

Malandra, James L.; Mills, Nancy S.; Kadlecek, Daniel E.; Lowery, John A.

doi:10.1021/ja00104a074

Cited by 38 publications

(76 citation statements)

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“…While it is difficult to compare chemical shifts in different solvents, this data suggests slightly greater antiaromaticity for the dianion over the corresponding monanion. This is consistent with the increased antiaromaticity of the dication of tetrabenzo[5.5]fulvalene, 8 in comparison with the corresponding fluorenyl monocation. 28 The calculated NICS values of dianion 3 2-were more positive, supporting its greater antiaromaticity, than those of the corresponding monoanion 4 -, when evaluated per ring system.…”

Section: Comparison Of the Antiaromaticity Of Dianion 3 2-with Monoansupporting

confidence: 81%

Antiaromatic Dianions: Dianions of Dixanthylidene by Reduction and Attempted Excited-State Deprotonation

2011

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Section: Comparison Of the Antiaromaticity Of Dianion 3 2-with Monoansupporting

confidence: 81%

Antiaromatic Dianions: Dianions of Dixanthylidene by Reduction and Attempted Excited-State Deprotonation

2011

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“…The combination of direct pyrroleÀpyrrole bonding with an onorthogonal arrangemento fn orcorrole subunitsf urnishes ad imer with as trong electronic interaction between the subunits that has not been observed in previously reported dimerics peciesc ontaining two antiaromaticr ings. [31][32][33][34] The dimericc omplex 4 possesses four distinct and easily accessible oxidation states that may be exploited for the preparationo fs table bis(radical) systemsh aving either dianionic or dicationic character.T he magnetic and opticalp roperties of these and relateds ystems as well as their reactivity will be furthers tudied in our laboratories.…”

Section: Resultsmentioning

confidence: 99%

Towards Norcorrin: Hydrogenation Chemistry and the Heterodimerization of Nickel(II) Norcorrole

Liu

Stępień

et al. 2015

Chemistry A European J

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5,14-Dimesitylnorcorrolatonickel(II) was hydrogenated under mild conditions (room temperature, 1 atm H2 , THF solution, 5 min.) in the presence of Raney nickel to yield nonaromatic derivatives that were isolated and characterized by NMR spectroscopy, UV/Vis spectrophotometry, HRMS, cyclic voltammetry, and X-ray diffraction analysis. The major hydrogenation product, 1,2,3,7,8,9-hexahydronorcorrolatonickel(II), underwent dimerization in the presence of p-chloranil to give a nonsymmetrically linked 2,3'-bis(norcorrole) system that can adopt eight different oxidation states over a redox potential window of 3 V and has a HOMO-LUMO gap of 0.92 V.

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“…The ring current model of aromaticity predicts a magnetic environment in the center of an aromatic ring that is opposite in sign to that of the periphery, resulting in protons that are shifted downfield when on the periphery of the aromatic species and would be shifted upfield if present in the center of the aromatic ring. These effects would be opposite for an antiaromatic species and these predictions have been given experimental support in the 1 H NMR characterization of [18]annulene and its dianion. 29 Nucleus independent chemical shifts, NICS, are based on this phenomenon, with the calculation of the magnetic shielding tensor for a dummy atom placed in the center of the ring system.…”

Section: Resultsmentioning

confidence: 74%

Dications of 3-Phenyl-indenylidene Dibenzo[a.d]cycloheptene: The Role of Charge in the Antiaromaticity of Cationic Systems

et al. 2010

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Dications of 9-(3-phenyl-1H-inden-1-ylidene)-5H-dibenzo[a,d]cycloheptene, 52þ , were prepared by oxidation with SbF 5 in SO 2 ClF, and their magnetic behavior was compared to dications of 9-(3-phenyl-1H-inden-1-ylidene)-9H-fluorene, 2 2þ . The good correlation between the experimental 1 H NMR shifts for the dications that were oxidized cleanly and the chemical shifts calculated by the GAIO method supported the use of the nucleus independent chemical shifts, NICS, to evaluate the antiaromaticity of the indenyl systems of 2 2þ /5 2þ and their unsubstituted parent compounds, 6 2þ and 7 2þ , as well as the antiaromaticity of the fluorenyl system of 2 2þ /7 2þ and the aromaticity of the dibenzotropylium system of 5 2þ /6 2þ . Antiaromaticity was shown to be directly related to the amount of charge in the antiaromatic systems, with the antiaromatic systems more responsive to changes in the calculated NBO charge than the aromatic systems. The antiaromaticity was also shown to be directly related to the amount of delocalization in the ring system. The aromaticity of the dibenzotropylium system was much less responsive to changes in the amount of charge in the tropylium system, because the aromatic system was much more completely delocalized. Thus, antiaromatic species are more sensitive probes of delocalization than aromatic ones.

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Dications of Tetrabenzofulvalenes. Paratropicity and .sigma. Donation in Perpendicular Antiaromatic Systems

Cited by 38 publications

References 0 publications

Antiaromatic Dianions: Dianions of Dixanthylidene by Reduction and Attempted Excited-State Deprotonation

Antiaromatic Dianions: Dianions of Dixanthylidene by Reduction and Attempted Excited-State Deprotonation

Towards Norcorrin: Hydrogenation Chemistry and the Heterodimerization of Nickel(II) Norcorrole

Dications of 3-Phenyl-indenylidene Dibenzo[a.d]cycloheptene: The Role of Charge in the Antiaromaticity of Cationic Systems

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