Electron diffraction and quantum chemical study of the structure and internal rotation in nitroethane

In the ED analysis, parameters of equilibrium geometry were refined simultaneously with scaling of quantum chemical force matrix aimed at fitting experimental vibrational frequencies. The data processing has shown the minimum of the potential energy function of internal rotation of NO2 group corresponding to the syn-C molecular configuration with torsional angle τ(CCNO) = 0°. Rotation of the nitro group was found to be slightly hindered, with potential energy barrier height in the range of 50-200 cm−1 (with the most probable value near 120 cm−1). The refined parameters of equilibrium molecular configuration are the following: re(CC) = 1.509(3) Å, re(CN) = 1.503(3) Å, re(NO) = 1.213(3) and 1.215(3) Å, ∠e(CCN) =  112.3(9)°, ∠e(ONO) = 125.9(5)°.