Aromatic pathways in conjugated rings connected by single bonds

Taubert, Stefan; Kaila, Ville R. I.; Sundholm, Dage

doi:10.1002/qua.22869

Cited by 20 publications

(22 citation statements)

References 50 publications

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“…For parallel to the molecular plane orientations, a short‐ranged shielding region is denoted owing to local C−C currents, similar to benzene. Such results are in line to the decribed previously by analysis of the canonical orbital contributions to the magnetic fields and magnetically induced current densities denoting that phenyl rings sustain a sizable aromatic character similar to isolated benzene …”

Section: Resultssupporting

confidence: 92%

Interplay Between Planar and Spherical Aromaticity: Shielding Cone Behavior in Dual Planar‐Planar, Planar‐Spherical and Spherical‐Spherical Aromatics

Muñoz-Castro

2020

ChemPhysChem

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The shielding cone concept is one of the most characteristic aspects of planar aromatic species. Herein, we explored how two neighbor aromatic moieties behave as dual planar‐planar, planar‐spherical, and spherical‐spherical species given by biphenyl, [PhCB11H11]−, and [CB11H11]22−, respectively. Our results show two separate aromatic regimes given by Clar's sextet and spherical aromatic states, with independent shielding cones sharing shielding regions of moderate strength, which can be extended for networks involving multiple independent aromatic states.

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Section: Resultssupporting

confidence: 92%

Interplay Between Planar and Spherical Aromaticity: Shielding Cone Behavior in Dual Planar‐Planar, Planar‐Spherical and Spherical‐Spherical Aromatics

Muñoz-Castro

2020

ChemPhysChem

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“…Calculations of spin and charge currents for open‐shell molecules are less accurate than the corresponding calculations for closed‐shell systems, because electron correlation effects are more important for open‐shell molecules. In addition spin‐contamination problems also appear …”

Section: Applicationsmentioning

confidence: 99%

Calculations of magnetically induced current densities: theory and applications

Sundholm

Fliegl

Berger

2016

WIREs Comput Mol Sci

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310

543

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A review of computational studies of magnetically induced current density susceptibilities in molecules and their relation to experiments is presented. The history of the investigation of magnetically induced current densities and ring currents in molecules is briefly covered. The theoretical development of relativistic and nonrelativistic computational approaches for computing current densities in closed-shell and open-shell molecules is discussed and different state of the art methods to interpret calculated current densities are reviewed. Numerical integration approaches to assess global, semilocal, and local aromatic properties of multiring molecules are presented and demonstrated on free-base trans-porphyrin. We show that numerical integration of the current density combined with guiding visualization techniques of the current flow is a powerful tool for studies of the aromatic character of complicated molecular structures such as annelated aromatic and antiaromatic rings. Representative applications are reported illustrating the importance of careful current density studies for organic and inorganic chemistry. The applications include calculations of current densities and current strengths for aromatic, antiaromatic, and nonaromatic molecules of different kind. Current densities in spherical, cylindrical, tetrahedral, toroidal, and Möbius-twisted molecules are discussed. The aromatic character, current pathways, and current strengths of porphyrins are briefly highlighted. Aromatic properties of inorganic molecules are assessed based on current density calculations. Current strengths as a noninvasive tool to determine strengths of hydrogen bonds are discussed.

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“…The pathways leading to structure 3 are barrierless and with similar energy profiles, irrespectively of the isomeric structure of the C 12 H 9 + reagent (o-, m-or p-). Hence they are not the rate limiting step in reaction (13) which, from structure 3 onward proceeds on a common path for all the starting isomers. This is in agreement with the similarities observed in the branching ratios for C 8 H 7 + starting from different neutral precursors, as reported in Table I.…”

Section: Onementioning

confidence: 99%

“…Hence polyphenyls are unsaturated polycyclic hydrocarbons but they do not belong to the family of PAHs for which the fusedbenzene ring structure maintains the aromatic character and a planar geometry when the number of C atoms increases. Alternatively, biphenyl and larger polyphenyls can be considered to consist of two or more crosslinked aromatic moieties [13]. The rationale underlying the proposal for the presence of polyphenyls in Titan's atmosphere is that they can form at lower temperatures with respect to PAHs, while still maintaining the possibility to grow to large polymeric structures and condensate to form aerosols.…”

Section: Introductionmentioning

confidence: 99%

Growth of polyphenyls via ion–molecule reactions: An experimental and theoretical mechanistic study

Aysina

Maranzana

Tonachini

et al. 2013

The Journal of Chemical Physics

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The reactivity of biphenylium cations C12H9(+) with benzene C6H6 is investigated in a joint experimental and theoretical approach. Experiments are performed by using a triple quadruple mass spectrometer equipped with an atmospheric pressure chemical ion source to generate C12H9(+) via dissociative ionization of various isomers of the neutral precursor hydroxybiphenyl (C12H10O). C-C coupling reactions leading to hydrocarbon growth are observed. The most abundant ionic products are C18H15(+), C18H13(+), C17H12(+), and C8H7(+). The dependence of product ion yields on the kinetic energy of reagent ions, as well as further experiments performed using partial isotopic labelling of reagents, support the idea that the reaction proceeds via a long lived association product, presumably the covalently bound protonated terphenyl C18H15(+). Its formation is found to be exothermic and barrierless and, therefore, might occur under the low pressure and temperature conditions typical of planetary atmospheres and the interstellar medium. Theoretical calculations have focussed on the channel leading to C8H7(+) plus C10H8, identifying, as the most probable fragments, the phenylethen-1-ylium cation and naphthalene, thus suggesting that the pathway leading to them might be of particular interest for the synthesis of polycyclic aromatic hydrocarbons. Both experiments and theory agree in finding this channel exoergic but hampered by small barriers of 2.7 and 3.7 kcal mol(-1) on the singlet potential energy surface.

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Aromatic pathways in conjugated rings connected by single bonds

Cited by 20 publications

References 50 publications

Interplay Between Planar and Spherical Aromaticity: Shielding Cone Behavior in Dual Planar‐Planar, Planar‐Spherical and Spherical‐Spherical Aromatics

Interplay Between Planar and Spherical Aromaticity: Shielding Cone Behavior in Dual Planar‐Planar, Planar‐Spherical and Spherical‐Spherical Aromatics

Calculations of magnetically induced current densities: theory and applications

Growth of polyphenyls via ion–molecule reactions: An experimental and theoretical mechanistic study

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