Bond Resonance Energy and Verification of the Isolated Pentagon Rule

Aihara, Jun

doi:10.1021/ja00119a029

Cited by 126 publications

(204 citation statements)

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“…All of them contain fused pentagons. Because abutting pentagons play critical roles in determining both the thermodynamic and kinetic properties of the fullerenes, 33,34 we hence analyzed the distribution patterns of pentagons for the 580 isomers. Finally, the stabilities of nonclassical C 54 isomers, those containing other sizes of ring such as square or heptagon, were also investigated to demonstrate their unstabilities.…”

Section: Isomers Of C 54mentioning

confidence: 99%

“…So, the chemical conditions in the fullerene reactor were extremely harsh and thereby required that all of the surviving molecules therein had considerable kinetic stabilities without labile sites; otherwise, they would decompose or be transformed to other stable forms. 34 This requirement gives us a valuable criterion for selecting the most likely experimental structures: only those C 54 Cl 8 isomers that have no kinetically unstable sites on the parent cage C 54 could be isolated and deserve further consideration.…”

Section: Isomers Containing Squares or Heptagonsmentioning

confidence: 99%

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The way of stabilizing non‐IPR fullerenes and structural elucidation of C₅₄Cl₈

Gao

Zhao

2007

J Comput Chem

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Recently, a new non-IPR chlorofullerene C(54)Cl(8) was isolated experimentally (Science 2004, 304, 699). To explore the ways to stabilize non-IPR fullerenes, the authors studied all of the possible isomers of C(54) fullerene and some of the C(54)Cl(8) isomers at PM3, B3LYP/3-21G, and B3LYP/6-31G* levels. Combined with analysis of pentagon distributions, bond resonance energies, and steric strains, C(54):540 with the least number of 5/5 bonds was determined to be the thermodynamically best isomer for the C(54)Cl(8). Based on C(54):540, the most probable structure of the experimental C(54)Cl(8) was elucidated. The results suggested one of the necessary conditions of stabilizing non-IPR fullerenes: chemical derivatizations of either endohedral complexation or exohedral addition need to sufficiently stabilize all of the kinetically unstable 5/5 bonds of the cages.

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Section: Isomers Of C 54mentioning

confidence: 99%

Section: Isomers Containing Squares or Heptagonsmentioning

confidence: 99%

The way of stabilizing non‐IPR fullerenes and structural elucidation of C₅₄Cl₈

Gao

Zhao

2007

J Comput Chem

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“…41,42 Note that peripheral π-bonds that belong to the same ring exhibit the same BRE values. 52 BREs for all π-bonds in 1a and 2a are positive in sign, indicating that all π-bonds contribute more or less to aromatic stabilization. These positive BREs are consistent with positive TREs for the two compounds although the converse is not always true.…”

Section: 28mentioning

confidence: 99%

“…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%

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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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Further test of the isolated pentagon rule: Thermodynamic and kinetic stabilities of C₈₄ fullerene isomers

Aihara¹,

Oe²,

Yoshida³

et al. 1996

J. Comput. Chem.

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Thermodynamic and kinetic stabilities of 73 C84 fullerene isomers were estimated from the MM3 heats of formation and the recently defined bond resonance energies (BREs), respectively. The BRE represents the contribution of a given π bond in a molecule to the topological resonance energy (TRE). All π bonds shared by two pentagons turned out to be highly reactive without exceptions. C84 fullerene isomers with such π bonds must be incapable of survival during harsh synthetic processes. Thus, the isolated pentagon rule (IPR) proved to be applicable to such large fullerene cages. For sufficiently large fullerenes like C84, some isolated‐pentagon isomers are also predicted to be very unstable with highly antiaromatic π bonds. © 1996 by John Wiley & Sons, Inc.

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Bond Resonance Energy and Verification of the Isolated Pentagon Rule

Cited by 126 publications

References 1 publication

The way of stabilizing non‐IPR fullerenes and structural elucidation of C₅₄Cl₈

The way of stabilizing non‐IPR fullerenes and structural elucidation of C₅₄Cl₈

Graph Theory of Ring-Current Diamagnetism

Further test of the isolated pentagon rule: Thermodynamic and kinetic stabilities of C₈₄ fullerene isomers

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Bond Resonance Energy and Verification of the Isolated Pentagon Rule

Cited by 126 publications

References 1 publication

The way of stabilizing non‐IPR fullerenes and structural elucidation of C54Cl8

The way of stabilizing non‐IPR fullerenes and structural elucidation of C54Cl8

Graph Theory of Ring-Current Diamagnetism

Further test of the isolated pentagon rule: Thermodynamic and kinetic stabilities of C84 fullerene isomers

Contact Info

Product

Resources

About

The way of stabilizing non‐IPR fullerenes and structural elucidation of C₅₄Cl₈

The way of stabilizing non‐IPR fullerenes and structural elucidation of C₅₄Cl₈

Further test of the isolated pentagon rule: Thermodynamic and kinetic stabilities of C₈₄ fullerene isomers