A ternary complex of aqua(18-crown-6)bis(o-nitrophenolato)barium(II), the triaqua(18-crown-6)(o-nitrophenolato)barium(II) cation and the o-nitrophenolate anion.

In the title compound [systematic name: triaqua(1,4,7,10,13,16-hexaoxacyclooctadecane-kappa(6)O)(2-nitrophenolato-kappaO)barium(II)-aqua(1,4,7,10,13,16-hexaoxacyclooctadecane-kappa(6)O)bis(2-nitrophenolato-kappa(2)O,O')barium(II)-2-nitrophenolate (1/1/1)], [Ba(C(12)H(24)O(6))(C(6)H(4)NO(3))(H(2)O)(3)][Ba(C(12)H(24)O(6))(C(6)H(4)NO(3))(2)(H(2)O)](C(6)H(4)NO(3)), the two Ba(II) atoms encapsulated by the 18-crown-6 rings have different coordinations. Although both Ba(II) atoms are coordinated to the six O atoms of the crowns, in the neutral moiety, the Ba(II) atom is coordinated to one terminal O atom from a water molecule, two phenolate O atoms and two nitro-group O atoms, while in the cationic moiety, the Ba(II) atom is coordinated to three terminal O atoms from water molecules and one phenolate O atom. Both the crowns are eclipsed and translated along the b direction. In the asymmetric unit, the three components are interconnected by four O-H.O interactions. The packing is stabilized by two intermolecular C-H.O interactions and by one O-H.O interaction.