Polymeric strontium ranelate nonahydrate

The title compound, poly[[mu-aqua-tetraaqua{mu-5-[bis(carboxylatomethyl)amino]-3-carboxylatomethyl-4-cyanothiophene-2-carboxylato}distrontium(II)] tetrahydrate], [Sr-2(C12H6N2O8S)(H2O)(5)]center dot 3.79H(2)O, crystallizes with nine- and eight-coordinated Sr2+ cations. They are bound to seven of the eight ranelate O atoms and five of the water molecules.

The SrO8 and SrO9 polyhedra are interconnected by edge-sharing, forming hollow layers parallel to (011). The layers are, in turn, interconnected by ranelate anions, forming a metal-organic framework (MOF) structure with channels along the a axis. The four water molecules not coordinated to strontium are located in these channels and hydrogen bonded to each other and to the ranelates.

Part of the water H atoms are disordered. The compound dehydrates very easily and 0.210 (4) water molecules out of nine were lost during crystal mounting causing additional disorder in the water structure.