Bond Resonance Energies and Kinetic Stabilities of Charged Fullerenes

Aihara, Jun

doi:10.1021/j100034a009

Cited by 67 publications

(107 citation statements)

References 10 publications

(11 reference statements)

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“…Similar to what is found for phenanthrene and pyrene, all local aromaticity methods coincide in assigning a larger aromaticity to the outer B than to the inner A 6-MRs of D 6h coronene. This result is in line with previous NICS, [46,71,72,74,75] HOMA, [72] and RCP calculations, [72] as well as ring-current analysis. [61,76] All indicators of aromaticity in Table 1 indicate that ring B of coronene is more aromatic than the corresponding B rings of phenanthrene and pyrene.…”

Section: Local Aromaticity Of the Free Pahssupporting

confidence: 92%

“…The GIAO method [43] has been used to perform calculations of NICS at ring centers (NICS(0)) determined by the nonweighted mean of the heavy-atom coordinates. As shown by Lazzeretti and Aihara, [44][45][46] the NICS(0) values contain important spurious contributions from the in-plane tensor components that are not related to aromaticity. So, to complement the NICS analysis, we also calculated the NICS(1) values, that is, NICS measured 1 below the center of the ring, on the opposite face to the ion for species interacting with a lithium cation.…”

Section: Computational Detailsmentioning

confidence: 90%

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Aromaticity Analysis of Lithium Cation/ π Complexes of Aromatic Systems

et al. 2005

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The changes in the local aromaticity of aromatic rings on complexation with lithium cation are discussed for a series of polycyclic aromatic hydrocarbons by using, as probes of aromaticity, the para-delocalization index (PDI), the aromatic fluctuation index (FLU), the harmonic oscillator model of aromaticity index (HOMA), and the nucleus-independent chemical shift (NICS). In most cases, changes in the electronically based PDI and FLU indices are almost irrelevant. For this reason, the analysis is carried out mainly with the more sensitive HOMA and NICS descriptors. These indices indicate that changes in the local aromatic character of the different rings are small. In general, Li+ interacts more favorably with the ring having the largest pi charge, but there is no correlation between these magnitudes. The ring directly interacting with the lithium cation suffers a slight but significant reduction of aromaticity, while the reduction of the local aromaticity of the adjacent rings is minor. For those rings located further away from the ring directly connected to Li+, we found generally a small increase in aromaticity. Although there is no clear correlation between aromaticity and Li+ binding enthalpies, there is a rough correlation between the latter and the change in the aromaticity of the ring directly interacting with the metal cation.

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Section: Local Aromaticity Of the Free Pahssupporting

confidence: 92%

Section: Computational Detailsmentioning

confidence: 90%

Aromaticity Analysis of Lithium Cation/ π Complexes of Aromatic Systems

et al. 2005

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“…It has been shown in detailed computations of p ring currents that, for coronene [90] and kekulene, [91] such a small current is the global result of two circular currents, one diatropic, the other paratropic, that rotate therefore in opposite directions around the concentric annulene ring located around the central hole. [92,93] Most certainly the same compensation of partial currents applies here for odd-layered doughnut species which contain an even (two or four) number of concentric "annulenoid" rings. Inversely, it is then logical to assume that, in even-layered doughnut species with, thus, an odd number of concentric "annulenoid" rings, the partial paratropic ring currents will not fully compensate the diatropic ones.…”

Section: Magnetic Propertiesmentioning

confidence: 56%

Aromaticity of Giant Polycyclic Aromatic Hydrocarbons with Hollow Sites: Super Ring Currents in Super‐Rings

Hajgató

Deleuze

Ohno

2006

Chemistry A European J

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We present a systematic theoretical study based on semi-empirical, Hartree-Fock (HF), and density functional theory (DFT) models of a series of polycyclic aromatic hydrocarbons (PAHs) that exhibit hollow sites. In this study we focus particularly on the magnetic criteria of aromaticity, namely (1)H NMR and nucleus-independent chemical shifts (NICS), and on their relationships with other electronic properties. The computed shifts and NICS indices indicate that an external magnetic field induces exceptionally strong ring currents in even-layered PAH doughnuts, in particular in the layer directly adjacent to the central hole of double-layered compounds. These exceptionally strong ring currents also correlate with particularly small HOMO-LUMO gaps and electronic excitation energies and to abnormally high polarizabilities, indicating in turn that these compounds have a more pronounced metallic character. Comparison is made with further depictions of aromaticity in these systems and in [18]-[66]annulene rings by employing topological, structural, and energetic criteria.

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“…Bond resonance energy (BRE) represents the contribution of a given π-bond to global aromaticity. 5,37,41,52,53 We defined BRE in the following manner in harmony with the TRE concept. The hypothetical reference π-system necessary to evaluate BRE for a given π-bond (e.g., a C 1 -C 2 bond in naphthalene 1) is obtained by modifying a pair of elements that correspond to this bond in the original secular determinant (eq 4) as follows: …”

Section: 28mentioning

confidence: 99%

Graph Theory of Ring-Current Diamagnetism

Aihara

2017

Bulletin of the Chemical Society of Japan

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Various magnetic criteria of aromaticity have been proposed so far, because they are easily calculated and applicable to a variety of cyclic π-systems. Many researchers, however, are reluctant to accept all or some of them. Our graph theory of ring-current diamagnetism revealed serious flaws in familiar magnetic criteria of aromaticity. Physically meaningful information on aromaticity can nevertheless be extracted from the ring-current diamagnetism. In particular, magnetic resonance energy (MRE), derived from the ring-current diamagnetic susceptibility, is interpretable as a kind of aromatic stabilization energy (ASE) and helps in consistently interpreting energetic and magnetic criteria of aromaticity. MRE and related quantities can be determined without reference to any hypothetical polyene-like structure but with a reasonable assumption that, when a magnetic field is applied to a cyclic π-system, a current is induced in each circuit in proportion to the ASE arising from the circuit. Unlike other conventional magnetic indexes, they are independent of the size and shape of the π-system.

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Bond Resonance Energies and Kinetic Stabilities of Charged Fullerenes

Cited by 67 publications

References 10 publications

Aromaticity Analysis of Lithium Cation/ π Complexes of Aromatic Systems

Aromaticity Analysis of Lithium Cation/ π Complexes of Aromatic Systems

Aromaticity of Giant Polycyclic Aromatic Hydrocarbons with Hollow Sites: Super Ring Currents in Super‐Rings

Graph Theory of Ring-Current Diamagnetism

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