The title polymeric compound, {(C3H12N2)[Co(C10H2O8)- (H2O)2]0.5H2O}n, was obtained by the reaction of cobalt(II) nitrate hexahydrate with the proton-transfer compound (pnH2)2(btc)2H2O (pn = propane-1,3-diamine and btcH4 = benzene-1,2,4,5-tetracarboxylic acid) in aqueous solution. Each Co2+ ion is situated on a crystallographic twofold rotation axis and is coordinated in a distorted octahedral geometry by six O atoms [Co—O = 2.0650 (9)–2.1107 (8) A ˚ ] from two coordinated water molecules and four (btc)4 ligands which also act as bridging ligands between Co2+ ions. In the crystal structure, a wide range of non-covalent interactions consisting of O—H O, N—H O and C— H O hydrogen bonds, as well as ion pairing, van der Waals forces and C—H stacking between the propane-1,3- diammonium ions and the aromatic rings of benzene-1,2,4,5- tetracarboxylate ligands, connect the various fragments, forming a three-dimensional supramolecular structure. The crystal studied was an inversion twin.
