catena-Poly[[silver(I)-μ-1,3-bis(4-pyridyl)propane] hemi(naphthalene-1,5-disulfonate) dihydrate]: a threedimensional metallo-supramolecular sandwich lamellar network

The title compound, {[Ag(C13H14N2)](C10H6O6S2)(0.5)center dot 2H(2)O}(n), (I), features a three-dimensional supramolecular sandwich architecture that consists of two-dimensional cationic layers composed of polymeric chains of silver(I) ions and 1,3-bis(4-pyridyl)propane (bpp) ligands, linked by Ag center dot center dot center dot Ag and pi-pi interactions, alternating with anionic layers in which uncoordinated naphthalene-1,5-disulfonate (nds(2-)) anions and solvent water molecules form a hydrogen-bonded network. The asymmetric unit consists of one Ag I cation linearly coordinated by N atoms from two bpp ligands, one bpp ligand, one half of an nds(2-) anion lying on a centre of inversion and two solvent water molecules. The two-dimensional {[Ag(bpp)](+)}(n) cationic and {[(nds)center dot 2H(2)O](2-)}(n) anionic layers are assembled into a three-dimensional supramolecular framework through long secondary coordination Ag center dot center dot center dot O interactions between the sulfonate O atoms and Ag I centres and through nonclassical C-H center dot center dot center dot O hydrogen bonds.