metal-organic compounds
5,6-Dioxo-1,10-phenanthroline-2,9-dicarboxylic acid dihydrate (H2pdda·2H2O), C14H6N2O6·2H2O, was obtained by carbonylation of 1,10-phenanthroline-2,9-dicarboxylic acid. Its first coordination compound, [MnCl(C14H6N2O6)(H2O)2]Cl·2H2O, in which the H2pdda ligand remains protonated, was synthesized in aqueous acetic acid. H2pdda chelates one water molecule via hydrogen bonds in H2pdda·2H2O, whereas in the coordination compound it chelates one heptacoordinate MnII atom via coordination bonds. The N atoms in H2pdda·2H2O and the Cl atoms in the coordination compound are also involved in hydrogen bonds. Extensive hydrogen bonding results in supramolecular networks in both compounds.