Effect of halo-substitution on the lowest-lying empty π* orbitals in benzene derivatives: Electron transmission and dissociative attachment spectra

Modelli, Alberto; Foffani, A.; Scagnolari, Francesco; Jones, Derek

doi:10.1016/0009-2614(89)80048-x

Cited by 48 publications

(36 citation statements)

References 26 publications

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“…Curves of 2-substituted halopyridines have no minimum, or the minimum is very shallow, whereas 3-and 4-substituted have quite clearly marked, although still rather flat minimum at larger C n -X distance, corresponding to the σ * dissociative state. The detachment of chlorine or bromine atom should be achievable at VEA energy, which is the confirmation of previous results of Modelli et al for 4-substituted pyridines [43]. Anions of halopyrazines according to DFT are stable, and the activation energy to pass to the σ * state is 3.79 kcal/mol and 5.78 kcal/mol for 2-bromo-and 2-chloropyrazine, respectively.…”

Section: Final Remarkssupporting

confidence: 88%

“…For the numbering of atoms, the reader is referred to Fig. 1 halogen anion formation from 4-ClPy and 4-BrPy at 0.26 eV and 0.10 eV, respectively, observed by Modelli et al [43]. The agreement between enthalpies obtained with the B3LYP functional and MP2 method in 6-31+G* basis is excellent for pyridine and pyrazine, but rather poor for halo derivatives.…”

Section: Potential Energy Curvesmentioning

confidence: 84%

“…The effect of the substituent on the orbitals in pyridine has been studied extensively (e.g., [41,42] and references therein). However, to the author's knowledge, there are no experimental or theoretical data on the interaction of electrons with halopyrazines and the only existing data concerning halo derivatives of pyridine, determined with electron transmission spectrometer (ETS), can be found in [31,43]. Electron affinities in their work were obtained as the vertical midpoint of the overall band in the derivative of the transmitted current spectra.…”

Section: Introductionmentioning

confidence: 99%

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DFT study of low-energy electron interaction with pyridine, pyrazine and their halo derivatives

Tańska

2021

Eur. Phys. J. D

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In this work, the density functional theory with B3LYP hybrid functional was employed to calculate quantities useful for estimating the behavior of pyridine, pyrazine and their derivatives monosubstituted with Cl or Br atom, when exposed to low-energy electron impact. Vertical electron affinities obtained in several Pople basis sets and in aug-cc-pVTZ basis set are reported. Although some of the investigated molecules do not form stable anions, the results are in a satisfactory agreement with the available, albeit sparse experimental data, if the diffuse functions are included in calculations. It was found that the 6-31+G* basis is sufficient and its further enlargement does not significantly change the results. At this level of theory, potential energy curves, supported by enthalpies of dissociation to the neutral and anion fragment, were also determined for the description of the dissociative electron attachment. According to B3LYP, the potential energy curves of the halogen bond are almost repulsive in halopyridines, whereas halopyrazine anions require small activation energy for dissociation. Vertical electron affinities, enthalpies and equilibrium C-X distances (X=H, Cl, Br) were also calculated using Møller-Plesset second-order perturbation theory. Graphic Abstract

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Section: Final Remarkssupporting

confidence: 88%

Section: Potential Energy Curvesmentioning

confidence: 84%

Section: Introductionmentioning

confidence: 99%

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DFT study of low-energy electron interaction with pyridine, pyrazine and their halo derivatives

Tańska

2021

Eur. Phys. J. D

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“…A more detailed description is reported in Ref. 15. Alternatively, the two halves of the collision chamber can be elec-trically shorted, with no voltage applied, in order to collect the total anion current, which is measured with a Keithley 485 picoammeter.…”

Section: Experimental and Computational Details Et And Da Spectramentioning

confidence: 99%

Low-energy electron capture in group 14 methyl chlorides and tetrachlorides: Electron transmission and dissociative electron attachment spectra and MS-Xα calculations

Modelli

Guerra

Jones

et al. 1998

The Journal of Chemical Physics

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Low-energy electron attachment to brominated methanesThe electron transmission and dissociative electron attachment spectra in the series of compounds (CH 3 ) 4Ϫn MCl n , with MϭC, Si, Ge, and Sn, are presented ͑except for the di-and trichloro germanium derivatives͒. The experimental resonance energies for temporary electron attachment to these compounds are compared with the total electron scattering cross sections obtained by means of continuum multiple-scattering ͑MS͒ X␣ calculations and with the attachment energies calculated with the bound-state MS-X␣ method, which also evaluates positive electron affinity values and provides the localization properties of the various empty orbitals. For all the compounds considered the LUMO is predicted to possess a 1 symmetry. The silicon and tin derivatives display the smallest and largest electron-acceptor properties, respectively. The measurements of the fragment anion current, as a function of the incident electron energy, reveal quite different behaviors in the various compounds with respect to dissociative electron attachment from both the quantitative and qualitative points of view.

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“…Such ring anion formation is generally characteristic of electron attachment to aromatic compounds, for e.g., benzene and pyridine as well as their derivatives. 42,43,45,47,[55][56][57] For instance, the generation of the C 5 H 4 N À anion (m/z ¼ 78) was also conrmed in the previous study of DEA to pyridine, 42 indicating three pronounced resonances at 2.5 eV, 5.3 eV, and 9.0 eV. Similarly, in close connection to the radiosensitizing properties of NA, such a formation of anionic species was also predicted in the studies of g radiolysis by Grimison et al 55 The C 5 H 4 N À anion yield shown in Fig.…”

Section: M/z ¼ 78mentioning

confidence: 99%

Negative ion formation and fragmentation upon dissociative electron attachment to the nicotinamide molecule

et al. 2021

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Effect of halo-substitution on the lowest-lying empty π* orbitals in benzene derivatives: Electron transmission and dissociative attachment spectra

Cited by 48 publications

References 26 publications

DFT study of low-energy electron interaction with pyridine, pyrazine and their halo derivatives

DFT study of low-energy electron interaction with pyridine, pyrazine and their halo derivatives

Low-energy electron capture in group 14 methyl chlorides and tetrachlorides: Electron transmission and dissociative electron attachment spectra and MS-Xα calculations

Negative ion formation and fragmentation upon dissociative electron attachment to the nicotinamide molecule

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