The planar equilibrium conformation of N-nitrosodimethylamine: A joint analysis of electron diffraction and microwave data with the use of quantum chemistry and vibrational spectroscopy

The equilibrium geometry, structure, relative energies of transition states for the internal rotation of the N=O and Me groups, and the potential function of wagging-inversion motion of the amino group NMe2 were calculated for the Me2NNO (1) molecule by the RHF and MP2(full) methods with the basis sets from 6-31G(d) to 6-311G(3df,2p). The transition frequencies for the nonrigid model of wagging-inversion motion were calculated by solving the direct one-dimensional problem. The calculation results were used in a joint analysis of the electron diffraction and microwave (for 10 isotopomers of 1) data including first-order perturbation theory calculations of nonlinear kinematic effects (h1). The electron diffraction data were analyzed within the framework of the dynamic model of large-amplitude motions in the amino group. Structure parameters were obtained. It was shown that the equilibrium conformation of the skeleton of 1 was planar (C-s symmetry) and the structure parameters were obtained. Close agreement of the quantum-chemical calculation results and the electron diffraction and microwave data used in the analysis was attained.