Crystal structure of catena-poly[[tetra­aqua­magnesium]-μ-(di­hydrogen hypodiphosphato)-κ(2) O:O′]

The crystal structure of the title compound, [Mg(H(2)P(2)O(6))(H(2)O)(4)](n), is built up from (H(2)P(2)O(6))(2−) anions bridging Mg(2+) cations into chains extending parallel to [011]. The Mg(2+) ion is located on an inversion centre and is octa­hedrally coordinated by the O atoms of two (H(2)P(2)O(6))(2−) anions and four water mol­ecules. The centrosymmetric (H(2)P(2)O(6))(2−) anion has a staggered conformation whereby the tetra­valent phospho­rus atom is surrounded tetra­hedrally 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 mol­ecules is present.