The resonance Raman spectrum of the 1,3,5-hexatriene radical cation generated by v-irradiation in a Freon glass is reported. The spectrum is excited at 395 nm in resonance with the second absorption band. Identical spectra are obtained from ionized (E)- and (Z)-1,3,5-hexatriene. The presence of more than one rotamer has to be assumed to account for all the observed resonance Raman bands. The bands are assigned to a mixture of the two rotamers, calculated at lowest energy, the ttt an tct rotamers, on the basis of ab initio ROHF/6-31G calculated harmonic frequencies. The spectrum indicates that the ttt and tct rotamers are formed in a ratio in the range 0.4./0.6-0.6/0.4. Two possible mechanisms are proposed to explain the presence of these two rotamers.
© 1994 American Chemical Society
Keszthelyi, T.; Wilbrandt, R.; Cave, R.J.; Johnson, J.L.* “Resonance Raman Investigation of the Radical Cation of 1,3,5-Hexatriene,” J. Phys. Chem. 1994, 98, 5632. doi: 10.1021/j100073a010