Nitrogen oxyanions

Nitrate is a polyatomic ion with the chemical formula . Salts containing this ion are called nitrates. Nitrates are common components of fertilizers and explosives. Almost all inorganic nitrates are soluble in water. An example of an insoluble (inorganic) nitrate is bismuth oxynitrate.

The nitrite ion has the chemical formula . Nitrite (mostly sodium nitrite) is widely used throughout chemical and pharmaceutical industries. The nitrite anion is a pervasive intermediate in the nitrogen cycle in nature. The name nitrite also refers to organic compounds having the –ONO group, which are esters of nitrous acid.

300px|thumb| Reactions of peroxynitrite leading to either apoptotic or necrotic cell death Peroxynitrite (sometimes called peroxonitrite) is an ion with the formula ONOO−. It is a structural isomer of nitrate, . Peroxynitrite is a potent reactive nitrogen species and is highly cytotoxic.

In chemistry, hyponitrite may refer to the anion ([ON=NO]2−), or to any ionic compound that contains it. In organic chemistry, it may also refer to the group −O−N=N−O−, or any organic compound with the generic formula R1−O−N=N−O−R2, where R1 and R2 are organic groups. Such compounds can be viewed as salts and esters of hyponitrous acid. An acid hyponitrite is an ionic compound with the anion ([HON=NO]−).

Orthonitrate is a tetrahedral anion of nitrogen with the formula . It was first identified in 1977 and is currently known in only two compounds, sodium orthonitrate (Na3NO4) and potassium orthonitrate (K3NO4). The corresponding oxoacid, orthonitric acid (), is hypothetical and has never been observed. Sodium and potassium orthonitrate can be prepared by fusion of the nitrate and metal oxide under high temperatures and ideally high pressures (several GPa).

Peroxynitrate (or peroxonitrate) refers to salts of the unstable peroxynitric acid, HNO4. Peroxynitrate is unstable and decomposes to nitrate and dioxygen.