Ab initio structures and vibrational analysis of two planar configurations of 1,3,5-hexatriene

Abstract The geometrical parameters of the tTt -hexatriene-1,3,5 and tCt -hexatriene-1,3,5 molecules have been computed at the RHF/6–31G level. The structures of both molecules are found to be planar in this approximation. The force fields of these molecules were calculated at the HF/6–31G//HF/6–31G level. The vibrational analyses of both molecules and their 2,3,4,5-tetradeuteroanalogues made it possible to refine the assignment of some experimental vibrational frequencies. The calculated mean amplitudes of vibrations of the non-deuterated molecules are compared with the experimental ones.