A three-dimensional hydrogen-bonded network in bis(4-hydroxyanilinium) selenate(VI) dihydrate.

The title compound, 2C(6)H(8)NO(+).SeO(4)(2-).2H(2)O, contains 4-hydroxyanilinium cations, selenate(VI) anions and water molecules. One of the two independent cations is nearly planar (excluding the ammonium H atoms), while the other is markedly nonplanar, with the hydroxy and ammonium groups displaced from the plane of the benzene ring. This results from the antiparallel orientation of the cations, which interact through oppositely polarized ammonium and hydroxy groups. Ionic and hydrogen-bonding interactions join the oppositely charged units into a three-dimensional network. This work demonstrates the usefulness of 4-aminophenol in the crystal engineering of organic-inorganic hybrid compounds.