Strontium disodium hexa­thio­diphosphate(IV) octa­hydrate

The crystal structure of SrNa(2)(P(2)S(6))·8H(2)O is isotypic with that of its calcium analogue. The asymmetric unit consists of one Sr(2+) cation (2 symmetry), two Na(+) cations (2 and [Image: see text] symmetry, respectively), one-half of a centrosymmetric (P(2)S(6))(4−) anion with a staggered confirmation and four water mol­ecules. The crystal structure is built up from layers of cations and anions extending parallel to (101). Each SrO(8) polyhedron is connected via edge-sharing to two NaO(4)S(2) octa­hedra and to one NaO(2)S(4) octa­hedron. The NaO(4)S(2) octa­edra are, in turn, connected with two (P(2)S(6))(4−) anions through common corners. Adjacent layers are held together by several O—H⋯S hydrogen-bonding inter­actions.