Bis(trimethyl­ammonium) naphthalene-1,5-disulfonate

The asymmetric unit of the title compound, 2C₃H₁₀N⁺·C₁₀H₆S₂O₆²⁻, contains a half-anion, which is completed by inversion symmetry, and one cation. The cations and anions are associated via strong N—H...O(sulfonate) hydrogen-bonding inter­actions, forming cation–anion–cation groups. Secondary inter­actions such as C—H(ammonium)...O(sulf­on­ate) and van der Waals inter­actions link the cations and anions together in a three-dimensional crystal structure, with zigzag rows of cations lying between layers of anions.

Bis(3-hy­droxy­propanaminium) naphthalene-1,5-disulfonate

In the title molecular salt, 2C₃H₁₀NO⁺·C₁₀H₆O₆S₂²⁻, the cations and anions are associated via N—H...O and O—H...O hydrogen-bonding inter­actions, giving rise to a three-dimensional structure with zigzag rows of cations lying between rows of anions. The asymmetric unit contains one cation and one half-anion, which is related to the remainder of the mol­ecule by an inversion center.

Methyl­ammonium tetra­fluoridoborate 18-crown-6 clathrate

In the title compound, CH₃NH₃⁺·BF₄⁻·C₁₂H₂₄O₆, the methyl­ammonium cation makes three N—H...O hydrogen bonds to the 18-crown-6 mol­ecule. The –NH₃⁺ and –CH₃ groups of the cation adopt a staggered conformation. The F atoms of the tetra­fluoridoborate anion are disordered over two sets of sites in a 0.519 (11):0.481 (11) ratio. Weak C—H...F inter­actions occur in the crystal, which possibly correlate with the anion disorder.