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Molecular structure and electronic spectrum of taspine: Semiempirical calculations

✍ Scribed by Tsuguo Sato; Masahiro Kataoka

Publisher
Journal of Heterocyclic Chemistry
Year
1999
Tongue
English
Weight
194 KB
Volume
36
Category
Article
ISSN
0022-152X

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✦ Synopsis

Abstract

AM1 calculations show that taspine has the three energy‐minima along the rotation‐like nuclear displacement of the dimethylaminoethyl group. They correspond to two enantiomeric structures and a Cs structure, which have nearly equal energies. The energy barrier between the enantiomeric structures and the Cs structure is calculated to be about 1 kcal/mol. The small barrier readily causes an intramolecular interconversion of the two enantiomers through the Cs structure and thus results in the optical inactivity of taspine. CNDO/S calculations show that the electronic spectra of the enantiomer and the Cs structure are quite similar. These calculated spectra are in good agreement with the observed electronic spectra.

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