A similar behaviour is also observed for the stretching of the CH bond in CHD2NO2, with a strong band at 3029 cm–1 corresponding to stretching perpendicular to the plane of the nitro group, and a weak band at 3014 cm–1 corresponding to stretching parallel to the same plane.79 The maximum frequency for the ν(CH) mode is found for the H-eclipsed geometry in both the harmonic and anharmonic treatment, and the frequency then decreases the further away the hydrogen atom is from the NO2 plane, in analogy to the observations for CH2DNO2.