The experimental liquid-phase spectrum of CHD2NO2 from ref. 81 is reproduced in Fig. 9 for comparison. The band between 2250 and 2290 cm–1, arising from the 21 mode in the harmonic treatment, is broadened in the anharmonic spectrum, mainly due to the 6191 combination of the four rotamers on the low-frequency side and to the 6181 combination bands on the high-frequency side of the D-eclipsed and H-eclipsed rotamers. Two weak peaks appear around 1920 and 2060 cm–1 due, respectively, to the 82 and 92 overtones, primarily from the D-staggered rotamer. A very weak band also appears around 2530 cm–1, corresponding to the 62 and 72 overtones, mainly from the D-staggered rotamer.