Ionized Bicyclo[2.2.2]oct-2-ene: A Twisted Olefinic Radical Cation Showing Vibronic Coupling

Nelsen, Stephen F.; Reinhardt, Laurie A.; Tran, Hieu Quang; Clark, Timothy; Chen, Guofei; Pappas, Robert S.; Williams, Ffrançon

doi:10.1002/1521-3765(20020301)8:5<1074::aid-chem1074>3.0.co;2-k

Cited by 10 publications

(8 citation statements)

References 22 publications

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“…(41)(42)(43)(44). 32 It is found that 41 is twisted (by about 11Њ) in agreement with ESR spectra and that the barrier to twisting is about 7 kJ mol Ϫ1 . An analysis of the orbitals and electronic states suggests that this is due to a pseudo Jahn-Teller effect.…”

Section: Delocalisation In Alkyl and Vinyl Cationssupporting

confidence: 56%

9 Computational organic chemistry

Yates

2003

Annu. Rep. Prog. Chem., Sect. B

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Section: Delocalisation In Alkyl and Vinyl Cationssupporting

confidence: 56%

9 Computational organic chemistry

Yates

2003

Annu. Rep. Prog. Chem., Sect. B

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“…As for the CO 3 molecule, considered above, combined JTE and PJTE multilevel and multimode problems are characteristic for the vibronic coupling for such systems. With regard to organic compounds, special attention should be paid to radical ions for which the energy gap to the excited states is small − (∼0.5–1.5 eV). Sound examples are given in the study of [111]propellane radical cation and bicyclo[2.2.2]oct-2-ene radical cation .…”

Section: Application To Molecular Systemsmentioning

confidence: 99%

“…With regard to organic compounds, special attention should be paid to radical ions for which the energy gap to the excited states is small − (∼0.5–1.5 eV). Sound examples are given in the study of [111]propellane radical cation and bicyclo[2.2.2]oct-2-ene radical cation . In the former case, a remarkable (unexpected) oxidative rearrangement takes place, in which three lateral framework bonds break and a normal C–C bond at the bridgehead position is reconstituted.…”

Section: Application To Molecular Systemsmentioning

confidence: 99%

Pseudo-Jahn–Teller Effect—A Two-State Paradigm in Formation, Deformation, and Transformation of Molecular Systems and Solids

2013

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“…Unfortunately, accurate ab initio post-Hartree−Fock methods tend to be too involved and computationally expensive to be currently applied to structural optimizations for the size of MV compounds of chemical or technological interest. Semiempirical CI approaches like the AM1-CISD method may partly correct the situation, ,− but their predictive power is limited. Today, the most widely used methodology to incorporate electron correlation for larger systems (within a formally single-determinant approach) is Kohn−Sham density functional theory (DFT).…”

Section: Introductionmentioning

confidence: 99%

A Reliable Quantum-Chemical Protocol for the Characterization of Organic Mixed-Valence Compounds

et al. 2009

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Structures, dipole moments, electron-transfer barriers, and spin density distributions of a series of mixed-valent bistriarylamin radical cations have been studied systematically by hybrid density functional methods with variable exact-exchange admixture combined with a continuum solvent model. The chosen systems differ in their bridging units and are all relatively close, from both sides, to the class II/III borderline of the Robin-Day classification of mixed-valence systems. Solvent effects are found to have a dramatic influence on the localized vs delocalized character of these cations. While gas-phase calculations or computations in a nonpolar solvent place all systems on the delocalized class III side, a more polar solvent like acetonitrile enables observation of symmetry breaking and charge localization with moderate exact-exchange admixtures in a hybrid functional for the systems on the class II side (with diphenylbutadiyne and diphenylethyne bridges). In contrast, the cations with the shortest bridges (phenylene, biphenylene) are characterized as class III. The comparison of computed intervalence charge-transfer excitation frequencies with experiment confirms the system with the diphenylbutadiyne bridge, and probably the system with the diphenylethyne bridge, to be class II, whereas in the dichloromethane solvent employed for spectroscopic measurements, the two other systems are on the class III side. Nonstandard hybrid density functional calculations with 35% Hartree-Fock-like exchange combined with continuum solvent models are suggested as a practical protocol for the quantum-chemical characterization of organic mixed-valence systems. This approach should allow closer examinations and provides a basis for the evaluation of other computational methods.

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Ionized Bicyclo[2.2.2]oct-2-ene: A Twisted Olefinic Radical Cation Showing Vibronic Coupling

Cited by 10 publications

References 22 publications

9 Computational organic chemistry

9 Computational organic chemistry

Pseudo-Jahn–Teller Effect—A Two-State Paradigm in Formation, Deformation, and Transformation of Molecular Systems and Solids

A Reliable Quantum-Chemical Protocol for the Characterization of Organic Mixed-Valence Compounds

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