N2O5\mathrm{N}_{2} \mathrm{O}_{5}N2O5
[NH4]+\left[\mathrm{NH}_{4}\right]^{+}[NH4]+
NO2\mathrm{NO}_{2}NO2
[NO2]−\left[\mathrm{NO}_{2}\right]^{-}[NO2]−