The molecule is a dicarboxylic acid dianion obtained by deprotonation of the carboxy groups of 4-nitro-6-oxohepta-2,4-dienedioic acid; major species at pH 7.3. It is a conjugate base of a 4-nitro-6-oxohepta-2,4-dienedioic acid.
(2E,4E)-4-nitro-6-oxohepta-2,4-dienedioate