Hexa-kis-(propyl-ammonium) benzene-1,2,4,5-tetra-carboxyl-ate 2,5-dicarb-oxy-benzene-1,4-carboxyl-ate tetra-hydrate.

The title organic salt, 6C(3)H(10)N(+)·C(10)H(2)O(8) (4-)·C(10)H(4)O(8) (2-)·4H(2)O, contains seven independent entities in the asymmetric unit which comprises three propyl-ammonium cations, two water mol-ecules, half a 2,5-dicarb-oxy-benzene-1,4-carboxyl-ate dianion (H(2)btc(2-)) and half a benzene-1,2,4,5-tetra-carboxyl-ate tetra-anion (btc(4-)), the latter two anions being located about centres of inversion. One of the water mol-ecules is disordered over two positions in a 0.55 (2):0.45 (2) ratio. The combination of mol-ecular ions and water mol-ecules results in an extensive and complex three-dimensional network of hydrogen bonds, the network being made up of nine unique N-H⋯O inter-actions between the ammonium cations and the anions, as well as four unique O-H⋯O inter-actions between the water mol-ecules and the anions.