Experimentally, two peaks are assigned in the infrared spectrum to the stretching mode of the C–D bond in CH2DNO2: A strong mode at 2266 cm–1 corresponding to the stretching perpendicular to the plane of the nitro group, and a weak one at 2276 cm–1 corresponding to the stretching parallel to the same plane.79 We find that the maximum frequency for the ν(CD) mode is found for the D-eclipsed geometry in both the harmonic and anharmonic treatment, and the frequency decreases the further away the deuterium atom is from the NO2 plane.