DOI: 10.17188/1754690
title: Materials Data on Mg4Si6H6O17 by Materials Project

description: Mg4Si6H2O17(H2)2 crystallizes in the orthorhombic Pnna space group. The structure is three-dimensional and consists of sixteen hydrogen molecules and one Mg4Si6H2O17 framework. In the Mg4Si6H2O17 framework, there are four inequivalent Mg2+ sites. In the first Mg2+ site, Mg2+ is bonded to six O2- atoms to form distorted MgO6 octahedra that share corners with four SiO4 tetrahedra and edges with three MgO6 octahedra. There are a spread of Mg–O bond distances ranging from 2.01–2.15 Å. In the second Mg2+ site, Mg2+ is bonded to six O2- atoms to form MgO6 octahedra that share corners with four SiO4 tetrahedra and edges with five MgO6 octahedra. There are four shorter (2.14 Å) and two longer (2.25 Å) Mg–O bond lengths. In the third Mg2+ site, Mg2+ is bonded in a distorted rectangular see-saw-like geometry to two equivalent H+0.33+ and four O2- atoms. Both Mg–H bond lengths are 2.38 Å. There is two shorter (1.98 Å) and two longer (2.01 Å) Mg–O bond length. In the fourth Mg2+ site, Mg2+ is bonded to six O2- atoms to form MgO6 octahedra that share corners with four equivalent SiO4 tetrahedra and edges with six MgO6 octahedra. There are a spread of Mg–O bond distances ranging from 1.97–2.14 Å. There are three inequivalent Si4+ sites. In the first Si4+ site, Si4+ is bonded to four O2- atoms to form SiO4 tetrahedra that share corners with three MgO6 octahedra and corners with three SiO4 tetrahedra. The corner-sharing octahedra tilt angles range from 53–61°. There is three shorter (1.64 Å) and one longer (1.65 Å) Si–O bond length. In the second Si4+ site, Si4+ is bonded to four O2- atoms to form SiO4 tetrahedra that share a cornercorner with one MgO6 octahedra and corners with three SiO4 tetrahedra. The corner-sharing octahedral tilt angles are 57°. There is two shorter (1.63 Å) and two longer (1.64 Å) Si–O bond length. In the third Si4+ site, Si4+ is bonded to four O2- atoms to form SiO4 tetrahedra that share corners with two MgO6 octahedra and corners with three SiO4 tetrahedra. The corner-sharing octahedra tilt angles range from 58–61°. All Si–O bond lengths are 1.64 Å. H+0.33+ is bonded in a single-bond geometry to one Mg2+ atom. There are nine inequivalent O2- sites. In the first O2- site, O2- is bonded in a 4-coordinate geometry to three Mg2+ and one O2- atom. The O–O bond length is 1.59 Å. In the second O2- site, O2- is bonded in a bent 150 degrees geometry to two Si4+ atoms. In the third O2- site, O2- is bonded in a rectangular see-saw-like geometry to three Mg2+ and one Si4+ atom. In the fourth O2- site, O2- is bonded in a rectangular see-saw-like geometry to three Mg2+ and one Si4+ atom. In the fifth O2- site, O2- is bonded in a bent 150 degrees geometry to two equivalent Si4+ atoms. In the sixth O2- site, O2- is bonded in a distorted trigonal planar geometry to two Mg2+ and one Si4+ atom. In the seventh O2- site, O2- is bonded in a bent 150 degrees geometry to two Si4+ atoms. In the eighth O2- site, O2- is bonded in a distorted bent 150 degrees geometry to two Si4+ atoms. In the ninth O2- site, O2- is bonded in a linear geometry to two equivalent Si4+ atoms.