Nitrosonium Nitrate. Isolation at 79°—205°K and Infrared Spectra of the Polymorphic Compound

Nitrosonium nitrate, NO+NO3−, a red solid, has been studied spectroscopically at temperatures ranging up to 205°K. Reproducible shifts of fundamental frequencies upon warming suggest two crystalline transformations between 79° and 205°K. The γ-, β-, and α-phase have been observed under nonequilibrium conditions in the following temperature ranges, respectively: 79°—185°, 167°—187°, 167°—205°K. The fundamental frequencies of the constituent ions in the γ, β, and α phase are: ν(NO)+: 2215, 2271, 2251 cm−1; ν3: 1364, 1324, 1328 cm−1; ν2: 819, 827, 812 cm−1; ν4: 716, 716, 711 cm−1.