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Potential‐energy surfaces in the lower excited states of benzene⇌Dewar–benzene isomerization process
Author(s) -
Tsuda Minoru,
Oikawa Setsuko,
Kimura Katsuhiko
Publication year - 1980
Publication title -
international journal of quantum chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.484
H-Index - 105
eISSN - 1097-461X
pISSN - 0020-7608
DOI - 10.1002/qua.560180122
Subject(s) - isomerization , benzene , chemistry , excited state , ground state , yield (engineering) , singlet state , photochemistry , intersystem crossing , quantum yield , triplet state , molecule , computational chemistry , atomic physics , thermodynamics , catalysis , organic chemistry , physics , quantum mechanics , fluorescence
Adiabatic potential‐energy surfaces in the lower excited states following the benzene⇌Dewar–benzene isomerization process were calculated by the INDO / S method postulating the concerted reaction mechanism which is proved to be valid in the ground state by the calculation of the intrinsic reaction coordinate. It was concluded that the benzene molecule in the 1 B 1 u and 1 E 2 u excited states readily isomerizes to Dewar–benzene in the condensed phase although the quantum yield may not be large. Bryce‐Smith's proposal, that the isomerization to Dewar–benzene occurs only after the intersystem crossing to the 3 B 1 u state in benzene molecule, will not be probable; for the 3 B 1 u route is not favorable to the isomerization in comparison with these singlet routes. However, the rearomatization of Dewar–benzene in the ground state may produce the 3 B 1 u benzene in small yield with higher yield of the ground‐state benzene. The activation energy in the rearomatization is calculated to be 19.03 kcal/mol. These conclusions are consistent with the experimental facts. Molecular orbital correlations in the isomerization and the ionization potentials of Dewar–benzene were also discussed.