Diethylenetriammonium oxonium naphthalene-1,6-disulfonate 3.5-hydrate

The title complex, C(4)H(16)N(3)(3+.)H(3)O(+.)2C(10)H(6)O(6)S(2)(2-.)3.5H(2)O, comprises one diethylenetriammonium trication, one oxonium cation, two naphthalene-1,6-disulfonate dianions and three-and-a- half water molecules. The oxonium cation donates a proton to each of three acceptors, forming strong hydrogen bonds, O-(HO)-O-... [2.476 (4), 2.473 (4) and 2.503 (4) angstrom]. O-(HO)-O-... and N-(HO)-O-... hydrogen bonds link the title complex into layers parallel to the (010) plane.