Diammonium tetra-kis-(iso-thio-cyanato)-zincate-1,4,10,13,16-hexa-oxa-cyclo-octa-deca-ne-water (1/2/1).

The title compound, (NH4)2[Zn(NCS)4]·2C12H24O6·H2O, the result of the reaction of ammonium thio-cyanate, 18-crown-6 and zinc(II) chloride in aqueous solution, exhibits an unusual supra-molecular structure. The Zn atom, two of the thio-cyanate chains and a water mol-ecule, disordered over two positions, lie on a mirror plane. The macrocycle adopts a conformation with approximate D 3d symmetry. The ammonium mol-ecules are contained within the bowl of the macrocycle via extensive N-H⋯O hydrogen bonds and the complex mol-ecules are linked via N-H⋯S hydrogen bonds, forming chains along the c-axis direction. The macrocycle is disordered over two positions [refined occupancy ratio = 0.666 (8):0.334 (8)]. The S atoms of two iso-thio-cyanate ligands are disordered within and about the mirror plane.