A supramolecular approach to the crystallization of polynuclear aqua ions has been developed which utilizes the ability of the donor atoms of macrocyclic ligands, such as 18-crown-6, to hydrogen-bond to coordinated water molecules, thereby modifying the 3D II-bonding network that surrounds such ions in aqueous solution. The synthesis, X-ray structure, and magnetic properties of [Cr-2(mu-OH)(2)(H2O)(8)][(H3C)(3)C6H2SO3](4) . C12H24O6 . 3H(2)O are reported.