The structure of sodium nitrite at 150°, 185°, 225°C†

The structure of NaN02 has been determined at 150°C, 185°C and 225°C. The first temperature is in the ferroelectric region, the second and third well above the transition. There is no free or even hindered rotation noticeable above the transition, up to 225°. At 150°C we postulate that a small percentage of the N02 group undergoes rotation. There are indications of this rotation in both Fourier and least squares analysis.