The role of H-bonds in charge transfer in the crystal of 1,5-naphthalenedisulfonic acid tetrahydrate

Electron density analysis in the title compound has revealed that, due to H-bond formation, the total charges of the dianion and H₅O₂⁺ cation are substantially decreased and bond length distribution in the SO₃ moiety can be directly related to the total energy of the cation–anion interactions and partial charges.