ELECTRONIC AND VIBRATIONAL STATES OF THE PLEIADIENES1
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Date
1956
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Ohio State University
Abstract
The electronic spectra of $acepleiadiene^{3}$ and $acepleiadylene^{4}$ have been studied in rigid glassy solution at $77^{\circ} K$, in dilute single mixed crystals with pyrene at $77^{\circ} K$ and at $4^{\circ} K$, and in single crystals at $77^{\circ} K$, The electronic transitions are assigned, using both the semi-empirical (Platt) and the symmetry classifications. Comparisons with theory where possible, indicate that the LCAO-MO, FEMO, and cyclicpolyene (Moffitt perturbation) theories are in good agreement with the observed results. Aromaticity in peri-condensed systems is discussed, and possible extensions of the Huckel $(4n+2)$ rule are suggested. Vibrational analyses and assignments are given for the lowest absorption and fluorescence transitions in acepleiadylene and for the lowest absorption transition in acepleiadiene. A $1890 cm^{-1}$ (K) crystal splitting which is observed for the lowest transition in acepleiadylene is interpreted on the basis of the Frenkel-Davydov exciton theory. The lowest absorption transition of acepleiadiene shows evidence of crystal-induced mixing of molecular transitions. The crystal spectra give information regarding some of the gross features of the crystal structure.
Description
$^{1}$ J. Am. Chem. Soc. 78, in press (1956). This research was supported by the U.S. Office of Ordnance Research under contract DA-30-115-Ord 620 with the University of Rochester. $^{2}$ Post-doctoral fellow under a grant by the Shell Fellowship Committee to the Department of Chemistry of the University of Rochester. $^{3}$ V. Boekelheide, W. E. Langeland, and C. T. Liu, J. Am. Chem. Soc. 73, 2432 (1951). $^{4}$ V. Boekelheide and G. K. Vick, J. Am. Chem. Soc. 78, 653 (1956)""
Author Institution: Department of Chemistry, The University of Rochester
Author Institution: Department of Chemistry, The University of Rochester