Knowledge Bank

Interest in the oxides of nitrogen has increased rapidly as speculation about their effects in the upper atmosphere has gained publicity. In considering the reactions which may occur, extensive data has been available on $NO2=$, $NO2-$, and $NO2$. Very little information has been published on the chemically reactive $NO2=$ species. The infrared spectrum of $NO2+$ has been studied in the solid compound $NO2$$BF4$ and in alkali halide solid solutions. The fundamental assignments in $NO2$$BF4$ are $\nu 1$ = 1043 cm$\mathrm{<mrow\; data-mjx-texclass="ORD">-1</mrow>}$ (Raman), $\nu 2$ = 593 cm$\mathrm{<mrow\; data-mjx-texclass="ORD">-1</mrow>}$ (I.R.), $\nu 3$ 2382 cm$\mathrm{<mrow\; data-mjx-texclass="ORD">-1</mrow>}$ (I.R.). $\nu 2$ had not been observed previously, while $\nu 3$ had been misassigned. The chemical reactivity of $NO2+$ is so great that it is difficult to prepare, and to maintain, at high purity. The $NO2$$BF4$ was found to contain appreciable quantities of $NO+$, and the spectra were separated by controlled thermal decomposition of the $NO2$$BF4$. The frequencies observed for $NO+$ are 2337 cm$\mathrm{<mrow\; data-mjx-texclass="ORD">-1</mrow>}$ (I.R.) and 2343 cm$\mathrm{<mrow\; data-mjx-texclass="ORD">-1</mrow>}$ (Raman), both in $NO2$$BF4$. In the isolation of $NO2+$ and $NO+$ in alkali halide matrices, quantities of NOX and $NO2$X were produced (X = halogen), as wel as other reaction products which have not been fully identified.