Neutral and cation 1,2-dichloropropane molecular structures and energies investigated by DFT and ab initio methods

A theoretical investigation on the molecular structures of the isolated 1,2-dichloropropane (C3H6Cl2) 3 H 6 Cl 2 ) neutral and its molecular cation was performed using high levels of density functional theory and ab initio methods. Three stable structural conformers have been found for the neutral molecule, with the Trans conformation being the most stable by about 5.8 kJ/mol on average in comparison with the ( + ) Gauche and (- ) Gauche conformations. As for the molecular cation, five stable conformational structures have been determined with energy differences within about 25 kJ/mol, and with the (- ) Near Cis conformer being the most stable cation species. The computed vibrational frequencies were compared with experimental values and the main IR spectral features assigned. The theoretical first adiabatic ionization energy of has been determined as 10.69 +/- 0.05 eV, from the corresponding neutral and cation molecular energies, via ab initio composite methods, and is in good agreement with the experimental value from photoelectron spectroscopy.