Proton-transfer compounds of 8-hydroxy-7-iodo­quinoline-5-sulfonic acid (ferron) with 4-chloro­aniline and 4-bromo­aniline

The crystal structures of the proton-transfer compounds of ferron (8-hydr­oxy-7-iodo­quinoline-5-sulfonic acid) with 4-­chloro­aniline and 4-bromo­aniline, namely 4-chloro­anilinium 8-hydr­oxy-7-iodo­quinoline-5-sulfonate monohydrate, C₆H₇ClN⁺·C₉H₅INO₄S^-·H₂O, and 4-bromo­anilinium 8-hydr­oxy-7-­iodo­quinoline-5-sulfonate monohydrate, C₆H₇BrN⁺·C₉H₅INO₄S^-·H₂O, have been determined. The compounds are isomorphous and comprise sheets of hydrogen-bonded cations, anions and water mol­ecules which are extended into a three-dimensional framework structure through centrosymmetric R₂²(10) O-H...N hydrogen-bonded ferron dimer inter­actions.

Pseudopolymorphism in brucine: brucine–water (1/2), the third crystal hydrate of brucine

The structure of a third pseudopolymorphic hydrate of brucine, brucine–water (1/2) [systematic name: 2,3-dimethoxy­strychnidin-10-one–water (1/2)], C₂₃H₂₆N₂O₄·2H₂O, has been determined at 130 K. The asymmetric unit comprises two independent brucine mol­ecules and four water mol­ecules of solvation. The four water mol­ecules form uncommon cyclic hydrogen-bonded homomolecular R₄⁴(8) tetra­mer rings, which then form primary hydrogen-bonded chain substructures extending down the 2₁ screw axis in the unit cell. The two brucine mol­ecules are linked peripherally to these substructures by either single O—H...N_brucine or asymmetric three-centre O—H...O_brucine hydrogen bonds.