Structures and vibration spectra of the C sub(i) and C sub(2) conformers of gauche,Trans,trans,Trans, gauche-octa-1,3,5,7-tetraene

The recent vibrational analysis of the experimental IR spectra of the non-planar gauche,Trans,trans,Trans,gauche possible rotational isomers of octa-1,3,5,7-tetraene (C sub(i) and C sub(2)) is reconsidered. Calculations of the vibrational frequencies of the non-planar C sub(i) and C sub(2) conformers of C sub(8)H sub(10) and C sub(8)D sub(10) are performed. Some of the calculated vibrational frequencies of the non-planar C sub(i) conformer are reassigned. Comparison of the IR experimental frequencies with the calculated frequencies for the two non-planar conformers suggests that all experimental bands belong to the non-planar C sub(2) conformer.