A Theoretical Determination of the Low-lying Electronic States of the<i>p</i>-Benzosemiquinone Radical Anion

Pou-Amérigo, Rosendo; Serrano‐Andrés, Luis; Merchán, Manuela; Ortí, and Enrique; Forsberg, Niclas

doi:10.1021/ja994402m

Cited by 51 publications

(92 citation statements)

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“…At the CASSCF level, the energy of radical anions tends to be overestimated with respect to that of the corresponding neutral molecules, although the results represent, however, well-localized solutions for valence-bound states in anions. [23][24][25] Therefore, the usual computational strategy of obtaining optimized geometries at the CASSCF level and performing fixed-geometry CASPT2 calculations can be used safely, considering that has proved its accuracy before. 26 Prior to the discussion of the reaction paths leading to the breaking of the C-N bond in nitromethane radical anion or to its isomerization to methylnitrite radical anion (CH 3 ONO Ϫ ), all stationary points on the doublet potential energy surfaces are presented ͑Fig.…”

Section: A Electronic Structure Of the Valence-bound State Of Nitrommentioning

confidence: 99%

“…They have proved to be accurate to deal with valence-bound anionic states in different systems. [23][24][25] B. Dissociation of the radical anion into methyl radical "CH 3 … and nitrite ion "NO 2 À … Figure 2 displays the CASPT2 potential energy curves (C s symmetry͒ for the dissociation of the ground electronic states of the radical anion and the neutral molecule, yielding as final products NO 2 Ϫ plus CH 3 in the doublet state ͓Fig. 2͑a͔͒ and NO 2 plus CH 3 on the singlet surface ͓Fig.…”

Section: A Electronic Structure Of the Valence-bound State Of Nitrommentioning

confidence: 99%

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Multiconfigurational second-order perturbation study of the decomposition of the radical anion of nitromethane

Arenas

Otero

Peláez

et al. 2004

The Journal of Chemical Physics

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The doublet potential energy surfaces involved in the decomposition of the nitromethane radical anion (CH 3 NO 2 Ϫ ) have been studied by using the multistate extension of the multiconfigurational second-order perturbation method ͑MS-CASPT2͒ in conjunction with large atomic natural orbital-type basis sets. A very low energy barrier is found for the decomposition reaction:No evidence has been obtained on the existence of an isomerization channel leading to the initial formation of the methylnitrite anion (CH 3 ONO Ϫ ) which, in a subsequent reaction, would yield nitric oxide ͑NO͒. In contrast, it is suggested that NO is formed through the bimolecular reaction:In particular, the CASSCF/MS-CASPT2 results indicate that the methylnitrite radical anion CH 3 ONO Ϫ does not represent a minimum energy structure, as concluded by using density functional theory ͑DFT͒ methodologies. The inverse symmetry breaking effect present in DFT is demonstrated to be responsible for such erroneous prediction.

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Section: A Electronic Structure Of the Valence-bound State Of Nitrommentioning

confidence: 99%

Section: A Electronic Structure Of the Valence-bound State Of Nitrommentioning

confidence: 99%

Multiconfigurational second-order perturbation study of the decomposition of the radical anion of nitromethane

Arenas

Otero

Peláez

et al. 2004

The Journal of Chemical Physics

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“…In most cases the excitation energies are within Ϯ 0.2 eV of the experimental estimates (when comparison with experimental data is appropriate). Particularly connected to the present study are the investigations carried out on the trans-cis photoisomerization of retinal (18,19), stilbene (20,21), and styrene (22,23), as well as the determination of the electronic spectra of anions (24,25).…”

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On the absorbance changes in the photocycle of the photoactive yellow protein: A quantum-chemical analysis

Molina

Merchán

2001

Proc. Natl. Acad. Sci. U.S.A.

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“…Gas-phase 12,[18][19][20] and computational [21][22][23][24] studies have already provided tantalising glimpses of the remarkable nature of pBQ as an electron acceptor. pBQ is planar both as a neutral and radical anion with D 2h symmetry and has ground states of 1 A g and 2 B 2g symmetry, respectively.…”

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Ultrafast above-threshold dynamics of the radical anion of a prototypical quinone electron-acceptor

et al. 2013

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. (2013) 'Ultrafast above-threshold dynamics of the radical anion of a prototypical quinone electron-acceptor.', Nature chemistry., 5 (8). pp. 711-717. Further information on publisher's website:https://doi.org/10.1038/nchem.1705Publisher's copyright statement:Additional information: Use policyThe full-text may be used and/or reproduced, and given to third parties in any format or medium, without prior permission or charge, for personal research or study, educational, or not-for-pro t purposes provided that:• a full bibliographic reference is made to the original source • a link is made to the metadata record in DRO • the full-text is not changed in any way The full-text must not be sold in any format or medium without the formal permission of the copyright holders.Please consult the full DRO policy for further details. Quinones are found throughout nature as key electron acceptor intermediates, 1,2 with examples including plastoquinone which is involved in the electron transfer chain of photosystem II, and ubiquinone (coenzyme Q10) which plays a key role in aerobic cellular respiration. 3 The central moiety responsible for the electron accepting ability in quinones is para-benzoquinone (pBQ), shown in Figure 1c. Electron transfer reactions involving pBQ can be highly exergonic and are therefore often classed as being in the Marcus inverted region. [4][5][6][7][8][9][10] This is shown schematically by the green path in Figure 1a, where a barrier between the Gibbs free energy of the reactants and products lowers the rates of the electron transfer process. However, even in the earliest experimental verifications of the inverted region for intramolecular electron transfer, several electron acceptors based on pBQ showed marked deviations from the expected behaviour, with transfer rates approaching those of a barrierless reaction. 11 It has been proposed that such deviations may involve electronically excited states of the product radical anion of para-benzoquinone (pBQ• -), 12 which could provide reaction pathways that bypass the barrier, as shown in Figure 1a with purple arrows. Figure 1b shows the location of these resonances.From the point of view of an electron approaching pBQ, these anionic resonances in the detachment continuum can capture an electron. Subsequent formation of the anionic ground state through internal conversion would redistribute the excess internal energy amongst all the vibrational modes. In a condensed-phase environment, this energy will be quenched by the surroundings. However, the initially formed excited states of pBQ• -can be unbound with respect to electron loss. For the above picture to be feasible, internal conversion must be able to compete with autodetachment. Electron attachment spectra suggest that it can, 26-28 but how does this occur given that these resonances are in some cases > 1 eV above the detachment threshold?In order to gain a fundamental understanding of the processes involved following electron capture, it is necessary to observe the relaxation dynamics in real t...

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A Theoretical Determination of the Low-lying Electronic States of thep-Benzosemiquinone Radical Anion

Cited by 51 publications

References 55 publications

Multiconfigurational second-order perturbation study of the decomposition of the radical anion of nitromethane

Multiconfigurational second-order perturbation study of the decomposition of the radical anion of nitromethane

On the absorbance changes in the photocycle of the photoactive yellow protein: A quantum-chemical analysis

Ultrafast above-threshold dynamics of the radical anion of a prototypical quinone electron-acceptor

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