Crystal structure of catena-poly[[tetra-aqua-magnesium]-μ-(di-hydrogen hypodiphosphato)-κ(2) O:O']

The crystal structure of the title compound, [Mg(H2P2O6)(H2O)4] n , is built up from (H2P2O6)(2-) anions bridging Mg(2+) cations into chains extending parallel to [011]. The Mg(2+) ion is located on an inversion centre and is octa-hedrally coordinated by the O atoms of two (H2P2O6)(2-) anions and four water mol-ecules. The centrosymmetric (H2P2O6)(2-) anion has a staggered conformation whereby the tetra-valent phospho-rus atom is surrounded tetra-hedrally by three O atoms and by one symmetry-related P atom. A three-dimensional O-H⋯O hydrogen-bonded network of medium strength involving the P-OH group of the anion and the water mol-ecules is present.