Materials Data on K2Ca2Mg(S2O9)2 by Materials Project
K2Ca2Mg(S2O9)2 crystallizes in the triclinic P-1 space group. The structure is three-dimensional. K is bonded in a 11-coordinate geometry to eleven O atoms. There are a spread of K–O bond distances ranging from 2.77–3.31 Å. Ca is bonded in a 8-coordinate geometry to eight O atoms. There are a spread of Ca–O bond distances ranging from 2.34–2.80 Å. Mg is bonded to six O atoms to form MgO6 octahedra that share corners with four SO4 tetrahedra. There are a spread of Mg–O bond distances ranging from 2.07–2.15 Å. There are two inequivalent S sites. In the first S site, S is bonded to four O atoms to form SO4 tetrahedra that share a cornercorner with one MgO6 octahedra. The corner-sharing octahedral tilt angles are 28°. There is two shorter (1.48 Å) and two longer (1.50 Å) S–O bond length. In the second S site, S is bonded to four O atoms to form SO4 tetrahedra that share a cornercorner with one MgO6 octahedra. The corner-sharing octahedral tilt angles are 51°. There are a spread of S–O bond distances ranging from 1.47–1.53 Å. There are nine inequivalent O sites. In the first O site, O is bonded in a 2-coordinate geometry to two equivalent K, one Ca, and one S atom. In the second O site, O is bonded in a 1-coordinate geometry to two equivalent K, one Ca, and one S atom. In the third O site, O is bonded in a distorted bent 150 degrees geometry to one Ca, one Mg, and one S atom. In the fourth O site, O is bonded in a distorted water-like geometry to one Ca and one S atom. In the fifth O site, O is bonded in a distorted single-bond geometry to two equivalent K, one Ca, and one S atom. In the sixth O site, O is bonded in a distorted single-bond geometry to two equivalent K, one Ca, and one S atom. In the seventh O site, O is bonded in a 3-coordinate geometry to one K, one Ca, one Mg, and one S atom. In the eighth O site, O is bonded in a 2-coordinate geometry to one K, one Ca, and one S atom. In the ninth O site, O is bonded in a bent 120 degrees geometry to one K and one Mg atom.