Hexaaquazinc(II) 3-ammonionaphthalene-1,5-disulfonate tetrahydrate

The title compound, [Zn(H2O)(6)][H3NC10H5(SO3)(2)](2).4H(2)O (Zn site symmetry 1), is isostructural with its nickel(II) and cobalt(II) analogues. An extensive network of N-H center dot center dot center dot O and O-H center dot center dot center dot O hydrogen bonds involving the ammonio group, water molecules, and sulfonate O atoms helps to establish the packing. One of the uncoordinated water molecules is disordered over at least two sites (modelled over two positions with site occupancy ratio ca 2: 1).