Tetrazine

Tetrazine is a compound that consists of a six-membered aromatic ring containing four nitrogen atoms with the molecular formula C₂H₂N₄. The name tetrazine is used in the nomenclature of derivatives of this compound. Three core-ring isomers exist: 1,2,3,4-tetrazines, 1,2,3,5-tetrazines, and 1,2,4,5-tetrazines, also known as v-tetrazines, as-tetrazines and s-tetrazines respectively.

1,2,3,4-Tetrazines are often isolated fused to an aromatic ring system and are stabilized as the dioxide derivatives.

1,2,4,5-Tetrazines are very well known and myriad 3,6-disubstituted 1,2,4,5-tetrazines are known. These materials are of use^[vague] in the area of energetic chemistry.^{[citation needed]}

Heavily substituted tetrazines form the verdazyls, a family of stable radicals.

Protected tetrazines are strong acetylene acceptors in Diels-Alder equilibria. For example, dipyridinyl 1,2,4,5-tetrazine abstracts acetylene from norbornadiene to cyclopentadiene and a pyridazine:

With norbornadiene fused to an arene the reaction stops at an intermediary stage.