Nitrosonium Ion Definition:

The NO+ ion, which is formed when NaNO2 is treated with HCl.

Nitrosonium Ion Explained:

The species nitroxyl ion and the nitrosonium cation are related to nitric oxide by reduction and oxidation of NO⋅ respectively, and each has distinctive chemistry unique to itself [3]. The fundamental chemistry of these three species is best rationalized in terms of MO theory. The nitroxyl anion, isoelectronic with dioxygen, has a bond order of 2. Nitric oxide is a radical, with a bond order of 2.5, the unpaired electron occupying an antibonding Pi- orbital.