An ab initio study of the structure, vibrational frequencies and force field for the symmetric form of N 2O 3

Abstract

In this work the structure of symmetric N 2O 3 was investigated using ab initio methods. Bond lengths and bond angles were determined using the 6-31G ∗ and the 6-311G ∗ basis sets and both SCF and MP2 theory. At the highest level of theory considered, the NO bond was determined to be 1.492 Å, the NO bond was 1.168 Å, the NON angle was 103.5 ° and the ONO bond angle was found to be 109.9 °. The molecule was determined to be planar at all levels of theory considered. Vibrational frequencies were computed for the symmetric structure of N 2O 3 at the 6-31G ∗/MP2 level of theory. The calculated vibrational frequencies are in better agreement with the alternate assignments than the preferred assignments reported previously. A new force field was derived for this molecule by starting with the theoretical values and making small adjustments in such a way as to reproduce the experimentally observed vibrational frequencies. An attempt was made to determine the relative stability of the symmetric and asymmetric forms of this molecule. Results are also compared with recent density functional calculations on these molecules.