Materials Data on Mg2H18Se2O17 by Materials Project
(MgH8SeO8)2H2O crystallizes in the monoclinic P2_1/c space group. The structure is three-dimensional and consists of four water molecules and one MgH8SeO8 framework. In the MgH8SeO8 framework, there are two inequivalent Mg2+ sites. In the first Mg2+ site, Mg2+ is bonded to six O2- atoms to form MgO6 octahedra that share corners with two SeO4 tetrahedra. There are a spread of Mg–O bond distances ranging from 2.08–2.15 Å. In the second Mg2+ site, Mg2+ is bonded to six O2- atoms to form MgO6 octahedra that share corners with two SeO4 tetrahedra. There are a spread of Mg–O bond distances ranging from 2.06–2.13 Å. There are sixteen inequivalent H1+ sites. In the first H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 1.00 Å. In the second H1+ site, H1+ is bonded in a single-bond geometry to two O2- atoms. There is one shorter (1.00 Å) and one longer (1.68 Å) H–O bond length. In the third H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.99 Å. In the fourth H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.99 Å. In the fifth H1+ site, H1+ is bonded in a single-bond geometry to two O2- atoms. There is one shorter (1.00 Å) and one longer (1.69 Å) H–O bond length. In the sixth H1+ site, H1+ is bonded in a single-bond geometry to two O2- atoms. There is one shorter (0.99 Å) and one longer (1.73 Å) H–O bond length. In the seventh H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.99 Å. In the eighth H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.98 Å. In the ninth H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 1.00 Å. In the tenth H1+ site, H1+ is bonded in a single-bond geometry to two O2- atoms. There is one shorter (1.00 Å) and one longer (1.69 Å) H–O bond length. In the eleventh H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.99 Å. In the twelfth H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 1.00 Å. In the thirteenth H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.98 Å. In the fourteenth H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.98 Å. In the fifteenth H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.99 Å. In the sixteenth H1+ site, 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 Se6+ sites. In the first Se6+ site, Se6+ is bonded to four O2- atoms to form SeO4 tetrahedra that share corners with two MgO6 octahedra. The corner-sharing octahedra tilt angles range from 38–53°. There are a spread of Se–O bond distances ranging from 1.67–1.69 Å. In the second Se6+ site, Se6+ is bonded to four O2- atoms to form SeO4 tetrahedra that share corners with two MgO6 octahedra. The corner-sharing octahedra tilt angles range from 31–52°. There are a spread of Se–O bond distances ranging from 1.66–1.69 Å. There are sixteen inequivalent O2- sites. In the first O2- site, O2- is bonded in a bent 150 degrees geometry to one Mg2+ and one Se6+ atom. In the second O2- site, O2- is bonded in a distorted water-like geometry to one Mg2+ and two H1+ atoms. In the third O2- site, O2- is bonded in a distorted water-like geometry to one Mg2+ and two H1+ atoms. In the fourth O2- site, O2- is bonded in a distorted trigonal planar geometry to one Mg2+ and two H1+ atoms. In the fifth O2- site, O2- is bonded in a distorted trigonal planar geometry to one Mg2+ and two H1+ atoms. In the sixth O2- site, O2- is bonded in a distorted water-like geometry to one Mg2+ and two H1+ atoms. In the seventh O2- site, O2- is bonded in a distorted trigonal non-coplanar geometry to two H1+ and one Se6+ atom. In the eighth O2- site, O2- is bonded in a bent 120 degrees geometry to one Mg2+ and one Se6+ atom. In the ninth O2- site, O2- is bonded in a single-bond geometry to one Se6+ atom. In the tenth O2- site, O2- is bonded in a bent 120 degrees geometry to one Mg2+ and one Se6+ atom. In the eleventh O2- site, O2- is bonded in a distorted single-bond geometry to one Se6+ atom. In the twelfth O2- site, O2- is bonded in a distorted trigonal planar geometry to one Mg2+ and two H1+ atoms. In the thirteenth O2- site, O2- is bonded in a distorted trigonal planar geometry to two H1+ and one Se6+ atom. In the fourteenth O2- site, O2- is bonded in a bent 150 degrees geometry to one Mg2+ and one Se6+ atom. In the fifteenth O2- site, O2- is bonded in a distorted water-like geometry to one Mg2+ and two H1+ atoms. In the sixteenth O2- site, O2- is bonded in a distorted water-like geometry to one Mg2+ and two H1+ atoms.