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

The title complex, C₄H₁₆N₃³⁺·H₃O⁺·2C₁₀H₆O₆S₂²⁻·3.5H₂O, 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—H...O [2.476 (4), 2.473 (4) and 2.503 (4) Å]. O—H...O and N—H...O hydrogen bonds link the title complex into layers parallel to the (010) plane.