Crystal structure of ethyl­ene­dioxy­tetra­thia­fulvalene-4,5-bis­(thiol­benzoic acid) 0.25-hydrate

In the title compound (systematic name: 4,4′-{[2-(5,6-di­hydro-[1,3]di­thiolo[4,5-b][1,4]dioxin-2-yl­idene)-1,3-di­thiole-4,5-di­yl]bis­(sulfanedi­yl)}di­benzoic acid 0.25-hydrate), C(22)H(14)O(6)S(6)·0.25H(2)O, the tetra­thia­fulvalene (TTF) core adopts a boat conformation, where the central S(2)C=CS(2) plane makes dihedral angles of 31.34 (4) and 26.83 (6)°, respectively, with the peripheral S(2)C=CS(2) and S(2)C(2)O(2) planes. In the crystal, the benzoic acid mol­ecules are linked via O—H⋯O hydrogen bonds, forming inversion dimers with R (2) (2)(8) motifs. The dimers are linked through weak C—H⋯O hydrogen bonds into a chain structure along [-101]. The chains stack along the a axis through S⋯S and S⋯C short contacts, forming layers parallel to the ac plane.