Chemical bonding in the pentagonal-pyramidal benzene dication and analogous isoelectronic hexa-coordinate species

Fantuzzi, Felipe; Sousa, David Wilian Oliveira de; Nascimento, Marco Antônio Chaer

doi:10.1016/j.comptc.2017.03.020

Cited by 25 publications

(21 citation statements)

References 61 publications

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“…Protonation of the apical carbon, for a variant lacking methyl substituents, leads to the pentagonal‐pyramidal C 6 H 6 dication, which has been studied both experimentally and computationally . Notably, the idea of an anionic Cp fragment was put forward . In related blog posts by Rzepa, a close relative of I , in which the apical carbon is protonated and the CH 3 groups on the five‐membered ring are retained, is studied.…”

Section: Resultsmentioning

confidence: 99%

The Pentagonal‐Pyramidal Hexamethylbenzene Dication: Many Shades of Coordination Chemistry at Carbon

Klein

Havenith

Knizia

2018

Chemistry A European J

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A recent report on the crystal structure of the pentagonal‐pyramidal hexamethylbenzene dication C6(CH3)6 2+ by Malischewski and Seppelt [Angew. Chem. Int. Ed. 2017, 56, 368] confirmed the structural proposal made in the first report of this compound in 1973 by Hogeveen and Kwant [Tetrahedron Lett. 1973, 14, 1665]. The widespread attention that this compound quickly gained led us to reinvestigate its electronic structure. On the basis of intrinsic bond orbital analysis, effective oxidation state analysis, ring current analysis, and comparison with well‐established coordination complexes, it is demonstrated that the central carbon atom behaves like a transition metal. The central (apical) carbon atom, although best described as a highly Lewis‐acidic carbon atom coordinated with an anionic cyclopentadienyl ligand, is also capable of acting as an electron‐pair donor to a formal CH3 + group. The different roles of coordination chemistry are discussed.

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Section: Resultsmentioning

confidence: 99%

The Pentagonal‐Pyramidal Hexamethylbenzene Dication: Many Shades of Coordination Chemistry at Carbon

Klein

Havenith

Knizia

2018

Chemistry A European J

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“…There are three great advantages of using this type of wave function to perform the interference energy analysis: (a) the atomic orbitals are uniquely defined within a given basis set (avoiding the arbitrariness involved in the choice of atomic orbitals); (b) the total interference energy and density per bond are automatically obtained; (c) contrary to Slater-type wave functions, GVB (and SCVB) wave functions are basis for the symmetric (or permutation) group as required by the permutation symmetry of the many-electrons Hamiltonian. The method has been applied to various classes of chemical species [51][52][53][54][55][56][57][58][59][60][61][62][63], diatomic and polyatomic molecules, with single, double and triple bonds, with different degrees of polarity, linear or branched, cyclic or not, conjugated and aromatics confirming that chemical bonds are formed due to the kinetic energy decrease caused by the quantum interference phenomenon taking place among the atomic orbitals involved in the bond, as predicted several decades ago by Ruedenberg [32]. The details of the method will not be presented but the interested reader may consult the appropriate literature [50,51].…”

Section: The Nature Of the Chemical Bond Quantum Interferencementioning

confidence: 99%

“…According to the ∆X AB criterion, the HF molecule should be the most polar and BH the less polar bond among the AH molecules, in disagreement with the experimental dipole moments. Moreover, the bond in HF and LiF should be considered "ionic" (H + F − and Li + F − ) [54][55][56][57][58][59][60][61][62][63][64]. In addition, this criterion furnishes wrong predictions not only of relative magnitudes of dipole moments but also of their signs.…”

Section: The Nature Of the Chemical Bond Quantum Interferencementioning

confidence: 99%

The Valence-Bond (VB) Model and Its Intimate Relationship to the Symmetric or Permutation Group

Nascimento

2021

Molecules

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VB and molecular orbital (MO) models are normally distinguished by the fact the first looks at molecules as a collection of atoms held together by chemical bonds while the latter adopts the view that each molecule should be regarded as an independent entity built up of electrons and nuclei and characterized by its molecular structure. Nevertheless, there is a much more fundamental difference between these two models which is only revealed when the symmetries of the many-electron Hamiltonian are fully taken into account: while the VB and MO wave functions exhibit the point-group symmetry, whenever present in the many-electron Hamiltonian, only VB wave functions exhibit the permutation symmetry, which is always present in the many-electron Hamiltonian. Practically all the conflicts among the practitioners of the two models can be traced down to the lack of permutation symmetry in the MO wave functions. Moreover, when examined from the permutation group perspective, it becomes clear that the concepts introduced by Pauling to deal with molecules can be equally applied to the study of the atomic structure. In other words, as strange as it may sound, VB can be extended to the study of atoms and, therefore, is a much more general model than MO.

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“…To the best of our knowledge, there is still no consensus on the global minimum structure of C 10 H 2+ 8 . The planar aromatic 10-membered ring depicted by Leach et al (1989a) and the bicyclic structure originated by the junction of the pentagonal pyramidal benzene dication (Jašík et al 2014;Fantuzzi et al 2017b) with the neutral benzene hexagonal ring are among the most prominent candidates.…”

Section: Mass Spectra and Production Of Ionsmentioning

confidence: 99%

Destruction and multiple ionization of PAHs by X-rays in circumnuclear regions of AGNs

Monfredini

Quitián-Lara

Fantuzzi

et al. 2019

Monthly Notices of the Royal Astronomical Society

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The infrared signatures of polycyclic aromatic hydrocarbons (PAHs) are observed in a variety of astrophysical objects, including the circumnuclear medium of active galactic nuclei (AGNs). These are sources of highly energetic photons (0.2 to 10 keV), exposing the PAHs to a harsh environment. In this work, we examined experimentally the photoionization and photostability of naphthalene (C 10 H 8 ), anthracene (C 14 H 10 ), 2methyl-anthracene (C 14 H 9 CH 3 ) and pyrene (C 16 H 10 ) upon interaction with photons of 275, 310 and 2500 eV. The measurements were performed at the Brazilian Synchrotron Light Laboratory using time-of-flight mass-spectrometry (TOF-MS). We determined the absolute photoionization and photodissociation cross sections as a function of the incident photon energy; the production rates of singly, doubly and triply charged ions; and the molecular half-lives in regions surrounding AGNs. Even considering moderate X-ray optical depth values (τ = 4.45) due to attenuation by the dusty torus, the halflives are not long enough to account for PAH detection. Our results suggest that a more sophisticated interplay between PAHs and dust grains should be present in order to circumvent molecular destruction. We could not see any significant difference in the half-life values by increasing the size of the PAH carbon backbone, N C , from 10 to 16. However, we show that the multiple photoionization rates are significantly greater than the single ones, irrespective of the AGN source. We suggest that an enrichment of multiply charged ions caused by X-rays can occur in AGNs.

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Chemical bonding in the pentagonal-pyramidal benzene dication and analogous isoelectronic hexa-coordinate species

Cited by 25 publications

References 61 publications

The Pentagonal‐Pyramidal Hexamethylbenzene Dication: Many Shades of Coordination Chemistry at Carbon

The Pentagonal‐Pyramidal Hexamethylbenzene Dication: Many Shades of Coordination Chemistry at Carbon

The Valence-Bond (VB) Model and Its Intimate Relationship to the Symmetric or Permutation Group

Destruction and multiple ionization of PAHs by X-rays in circumnuclear regions of AGNs

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