π*-σ* Hyperconjugation mechanism on the rotational barrier of the methyl group (II)

1- and 2-methylnaphthalenes in the S0, S1, C0, and A1 states

Hiromi Nakai, Y. Kawamura

    Research output: Contribution to journalArticle

    25 Citations (Scopus)

    Abstract

    Internal rotation of the methyl group in 1- and 2-methylnaphthalenes has been investigated by the ab initio theory. The rotational barriers in the S0 and S1 states calculated by the Hartree-Fock and configuration-interaction with single-excitation operator methods are in reasonable agreement with experimental values. The variations of the rotational barriers by excitation (S0→S1), ionization (S0→C0), and electron attachment (S0→A1) are shown to be directly connected with the stability of the HOMO and/or LUMO by the first-order treatment. In the HOMO and LUMO, a new type of orbital interaction named π*-σ* hyperconjugation appears and determines their stability. The interpretation based on the π*-σ* hyperconjugation can consistently and comprehensively explain the barrier variations.

    Original languageEnglish
    Pages (from-to)298-304
    Number of pages7
    JournalChemical Physics Letters
    Volume318
    Issue number4-5
    Publication statusPublished - 2000 Feb 25

    Fingerprint

    Ionization
    electron attachment
    configuration interaction
    excitation
    Electrons
    ionization
    operators
    orbitals
    1-methylnaphthalene
    2-methylnaphthalene
    interactions

    ASJC Scopus subject areas

    • Physical and Theoretical Chemistry
    • Spectroscopy
    • Atomic and Molecular Physics, and Optics

    Cite this

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    title = "π*-σ* Hyperconjugation mechanism on the rotational barrier of the methyl group (II): 1- and 2-methylnaphthalenes in the S0, S1, C0, and A1 states",
    abstract = "Internal rotation of the methyl group in 1- and 2-methylnaphthalenes has been investigated by the ab initio theory. The rotational barriers in the S0 and S1 states calculated by the Hartree-Fock and configuration-interaction with single-excitation operator methods are in reasonable agreement with experimental values. The variations of the rotational barriers by excitation (S0→S1), ionization (S0→C0), and electron attachment (S0→A1) are shown to be directly connected with the stability of the HOMO and/or LUMO by the first-order treatment. In the HOMO and LUMO, a new type of orbital interaction named π*-σ* hyperconjugation appears and determines their stability. The interpretation based on the π*-σ* hyperconjugation can consistently and comprehensively explain the barrier variations.",
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    T2 - 1- and 2-methylnaphthalenes in the S0, S1, C0, and A1 states

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    N2 - Internal rotation of the methyl group in 1- and 2-methylnaphthalenes has been investigated by the ab initio theory. The rotational barriers in the S0 and S1 states calculated by the Hartree-Fock and configuration-interaction with single-excitation operator methods are in reasonable agreement with experimental values. The variations of the rotational barriers by excitation (S0→S1), ionization (S0→C0), and electron attachment (S0→A1) are shown to be directly connected with the stability of the HOMO and/or LUMO by the first-order treatment. In the HOMO and LUMO, a new type of orbital interaction named π*-σ* hyperconjugation appears and determines their stability. The interpretation based on the π*-σ* hyperconjugation can consistently and comprehensively explain the barrier variations.

    AB - Internal rotation of the methyl group in 1- and 2-methylnaphthalenes has been investigated by the ab initio theory. The rotational barriers in the S0 and S1 states calculated by the Hartree-Fock and configuration-interaction with single-excitation operator methods are in reasonable agreement with experimental values. The variations of the rotational barriers by excitation (S0→S1), ionization (S0→C0), and electron attachment (S0→A1) are shown to be directly connected with the stability of the HOMO and/or LUMO by the first-order treatment. In the HOMO and LUMO, a new type of orbital interaction named π*-σ* hyperconjugation appears and determines their stability. The interpretation based on the π*-σ* hyperconjugation can consistently and comprehensively explain the barrier variations.

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