Hexa­kis­(propyl­ammonium) benzene-1,2,4,5-tetra­carboxyl­ate 2,5-dicarb­oxy­benzene-1,4-carboxyl­ate tetra­hydrate

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 propyl­ammonium cations, two water mol­ecules, half a 2,5-dicarb­oxy­benzene-1,4-carboxyl­ate dianion (H(2)btc(2−)) and half a benzene-1,2,4,5-tetra­carboxyl­ate tetra­anion (btc(4−)), the latter two anions being located about centres of inversion. One of the water mol­ecules is disordered over two positions in a 0.55 (2):0.45 (2) ratio. The combination of mol­ecular ions and water mol­ecules results in an extensive and complex three-dimensional network of hydrogen bonds, the network being made up of nine unique N—H⋯O inter­actions between the ammonium cations and the anions, as well as four unique O—H⋯O inter­actions between the water mol­ecules and the anions.