Urey-Bradley potential constants in nitrogen dioxide, nitrite ion and dinitrogen tetroxide

Abstract

The Urey-Bradley type force field has been applied to the calculation of vibrational force constants in three nitrogen oxides, NO 2, NO 2- and N 2O 4, which have in common the nitro group. For the nitrogen dioxide molecule three independent constants were adjusted to fit six observed frequencies from both 14N and 15N isotopic molecules by a least-squares method. An IBM 650 digital computer was programmed for the calculation on the tetroxide. Seven constants were used in this case, and these were fitted to nine observed in-planar mode frequencies by a least-squares method. The final set of potential constants for N 2O 4 was found to reproduce satisfactorily the frequencies of the isotopic molecule.