DOI: 10.17188/1284944
title: Materials Data on Ca2H2S2O9 by Materials Project

description: Ca2H2S2O9 crystallizes in the monoclinic C2 space group. The structure is three-dimensional. there are four inequivalent Ca2+ sites. In the first Ca2+ site, Ca2+ is bonded to eight O2- atoms to form distorted CaO8 hexagonal bipyramids that share corners with four SO4 tetrahedra, edges with two equivalent CaO8 hexagonal bipyramids, and edges with two equivalent SO4 tetrahedra. There are a spread of Ca–O bond distances ranging from 2.47–2.63 Å. In the second Ca2+ site, Ca2+ is bonded in a 4-coordinate geometry to two equivalent H1+ and eight O2- atoms. Both Ca–H bond lengths are 2.67 Å. There are a spread of Ca–O bond distances ranging from 2.32–2.75 Å. In the third Ca2+ site, Ca2+ is bonded to eight O2- atoms to form distorted CaO8 hexagonal bipyramids that share corners with four SO4 tetrahedra, edges with three CaO8 hexagonal bipyramids, and edges with two SO4 tetrahedra. There are a spread of Ca–O bond distances ranging from 2.42–2.64 Å. In the fourth Ca2+ site, Ca2+ is bonded in a 4-coordinate geometry to two H1+ and eight O2- atoms. There are one shorter (2.61 Å) and one longer (2.62 Å) Ca–H bond lengths. There are a spread of Ca–O bond distances ranging from 2.32–2.76 Å. There are three inequivalent H1+ sites. In the first H1+ site, H1+ is bonded in a single-bond geometry to one Ca2+ and one O2- atom. The H–O bond length is 0.98 Å. In the second H1+ site, H1+ is bonded in a single-bond geometry to one Ca2+ and one O2- atom. The H–O bond length is 0.98 Å. In the third H1+ site, H1+ is bonded in a single-bond geometry to one Ca2+ and one O2- atom. The H–O bond length is 0.98 Å. There are three inequivalent S6+ sites. In the first S6+ site, S6+ is bonded to four O2- atoms to form SO4 tetrahedra that share a cornercorner with one CaO8 hexagonal bipyramid and an edgeedge with one CaO8 hexagonal bipyramid. There are a spread of S–O bond distances ranging from 1.48–1.50 Å. In the second S6+ site, S6+ is bonded to four O2- atoms to form SO4 tetrahedra that share corners with two equivalent CaO8 hexagonal bipyramids and an edgeedge with one CaO8 hexagonal bipyramid. There is two shorter (1.48 Å) and two longer (1.50 Å) S–O bond length. In the third S6+ site, S6+ is bonded to four O2- atoms to form SO4 tetrahedra that share corners with three CaO8 hexagonal bipyramids and an edgeedge with one CaO8 hexagonal bipyramid. There are a spread of S–O bond distances ranging from 1.48–1.51 Å. There are fourteen inequivalent O2- sites. In the first O2- site, O2- is bonded in a 1-coordinate geometry to two Ca2+ and one S6+ atom. In the second O2- site, O2- is bonded in a 1-coordinate geometry to two Ca2+ and one S6+ atom. In the third O2- site, O2- is bonded in a 2-coordinate geometry to two equivalent Ca2+ and one S6+ atom. In the fourth O2- site, O2- is bonded in a 1-coordinate geometry to two equivalent Ca2+ and one S6+ atom. In the fifth O2- site, O2- is bonded in a 1-coordinate geometry to two Ca2+ and one S6+ atom. In the sixth O2- site, O2- is bonded in a 2-coordinate geometry to two Ca2+ and one S6+ atom. In the seventh O2- site, O2- is bonded in a 1-coordinate geometry to two equivalent Ca2+ and one S6+ atom. In the eighth O2- site, O2- is bonded in a 1-coordinate geometry to two equivalent Ca2+ and one S6+ atom. In the ninth O2- site, O2- is bonded in a 1-coordinate geometry to two Ca2+ and one S6+ atom. In the tenth O2- site, O2- is bonded in a 1-coordinate geometry to two Ca2+ and one S6+ atom. In the eleventh O2- site, O2- is bonded in a 1-coordinate geometry to two Ca2+ and one S6+ atom. In the twelfth O2- site, O2- is bonded in a 1-coordinate geometry to two Ca2+ and one S6+ atom. In the thirteenth O2- site, O2- is bonded in a water-like geometry to two equivalent H1+ atoms. In the fourteenth O2- site, O2- is bonded in a water-like geometry to two H1+ atoms.