[3][4] However, removal of three protons yields the melonate[5] (formerly hydromelonate[1]) anion (NCN)3(C6N7)3−, whose salts are stable and have been known since the 19th century.

[1] In the following years Liebig prepared the same salt by other methods, such as by fusing potassium thiocyanate with antimony trichloride,[7] and eventually determined the formula C9N13H3 for the acid.

[9] Starting in the 1970s, melonates have attracted new interest, motivated by research in cubic carbon nitride c-C3N4.

[3][5] Melonate salts decompose when melted with cyanates to form tricyanomelaminates, the first selective decomposition reaction leading from heptazines to triazines.

[2] Pyrolysis of iron(III) melonate Fe[C9N13] at very high temperature yields carbon in the form of nanotubes.