The first metal complex with the hydrazine dicarboxylate dianion: Na2(O2CNHNHCO2)(H2O)3

Na2(O2CNHNHCO2)(H2O)3 is the first complex of the hydrazinedicarboxylate dianion with a metal ion. In the crystal structure, there are three distinct sodium-ion coordination polyhedra, all approximating to octahedra: trans-NaO4(H2O)2, cis-NaO2(H2O)4 and trans-NaN2O4. The latter arises from the coordination of two bidenate-N,O and two monodentate-O ligands.