The molecule is a dicarboxylic acid dianion arising from deprotonation of both carboxy groups of 2-hydroxy-3-(3-oxoprop-1-enyl)but-2-enedioic acid; major species at pH 7.3. It is a conjugate base of a 2-hydroxy-3-(3-oxoprop-1-enyl)but-2-enedioic acid.
(E,2Z)-2-[carboxy(oxido)methylidene]-5-oxopent-3-enoate