Materials Data on KFeH2S2O9 by Materials Project
KFeH2S2O9 crystallizes in the monoclinic P2_1/m space group. The structure is three-dimensional. K1+ is bonded in a 10-coordinate geometry to ten O2- atoms. There are a spread of K–O bond distances ranging from 2.84–3.09 Å. Fe3+ is bonded to six O2- atoms to form FeO6 octahedra that share corners with five SO4 tetrahedra. There are a spread of Fe–O bond distances ranging from 1.98–2.07 Å. H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.99 Å. There are two inequivalent S6+ sites. In the first S6+ site, S6+ is bonded to four O2- atoms to form SO4 tetrahedra that share corners with three equivalent FeO6 octahedra. The corner-sharing octahedra tilt angles range from 37–47°. There are a spread of S–O bond distances ranging from 1.46–1.50 Å. In the second S6+ site, S6+ is bonded to four O2- atoms to form SO4 tetrahedra that share corners with two equivalent FeO6 octahedra. The corner-sharing octahedral tilt angles are 40°. There are a spread of S–O bond distances ranging from 1.46–1.52 Å. There are seven inequivalent O2- sites. In the first O2- site, O2- is bonded in a 2-coordinate geometry to one K1+, one Fe3+, and one S6+ atom. In the second O2- site, O2- is bonded in a distorted water-like geometry to one Fe3+ and two equivalent H1+ atoms. In the third O2- site, O2- is bonded in a bent 150 degrees geometry to one Fe3+ and one S6+ atom. In the fourth O2- site, O2- is bonded in a distorted single-bond geometry to three equivalent K1+ and one S6+ atom. In the fifth O2- site, O2- is bonded in a distorted single-bond geometry to one K1+ and one S6+ atom. In the sixth O2- site, O2- is bonded in a 2-coordinate geometry to one K1+, one Fe3+, and one S6+ atom. In the seventh O2- site, O2- is bonded in a single-bond geometry to two equivalent K1+ and one S6+ atom.