The molecular structure of methyl(vinyl)- N-nitroamine reinvestigated by gas phase electron diffraction and ab initio MO calculations

Abstract

The molecular structure of methyl(vinyl)- N-nitroamine has been reinvestigated by gas-phase electron diffraction and ab initio MO calculations. The methyl(vinyl)- N-nitroamine has been found from ab initio MO calculations to exist as a mixture of two conformers: an anti- and a syn-form, the former being more stable. The energy difference is predicted to be 3.3 kcal mol −1. The results obtained by the calculation were used to evaluate vibrational amplitudes required for further electron diffraction analysis. In the electron diffraction analysis some bond length and bond angle differences found by ab initio calculations were assumed. The vapour was assumed to consist only of the anti-form. The torsional angle around the NC vinyl and NN bonds were refined. It has been found that the amine group is planar. The vinyl group is out of the molecular plane by 19° ( r a-structure).