TY - JOUR
T1 - Π*–σ* Hyperconjugation mechanism on the rotational barrier of the methyl group (II)
T2 - 1- and 2-methylnaphthalenes in the S0, S1, C0, and A1 states
AU - Nakai, H.
AU - Kawamura, Y.
N1 - Funding Information:
Part of the calculations was performed at the Computer Center of the Institute for Molecular Science and the Media Network Center (MNC) of Waseda University. Part of this study was supported by a Grant-in-Aid for Scientific Research on Priority Areas `Molecular Physical Chemistry' from the Japanese Ministry of Education, Science, Sports, and Culture, and by a Waseda University Grant for Special Research Projects.
PY - 2000/2/25
Y1 - 2000/2/25
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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U2 - 10.1016/S0009-2614(00)00054-3
DO - 10.1016/S0009-2614(00)00054-3
M3 - Article
AN - SCOPUS:0000378060
SN - 0009-2614
VL - 318
SP - 298
EP - 304
JO - Chemical Physics Letters
JF - Chemical Physics Letters
IS - 4-5
ER -