Materials Data on Mg5H8O9 by Materials Project
(Mg(OH)2)3Mg(OH)2MgO crystallizes in the trigonal P-3m1 space group. The structure is two-dimensional and consists of three Mg(OH)2 sheets oriented in the (0, 0, 1) direction and one Mg(OH)2MgO sheet oriented in the (0, 0, 1) direction. In each Mg(OH)2 sheet, Mg2+ is bonded to six equivalent O2- atoms to form edge-sharing MgO6 octahedra. All Mg–O bond lengths are 2.10 Å. H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.97 Å. O2- is bonded in a distorted single-bond geometry to three equivalent Mg2+ and one H1+ atom. In the Mg(OH)2MgO sheet, Mg2+ is bonded to six O2- atoms to form a mixture of edge and corner-sharing MgO6 octahedra. The corner-sharing octahedral tilt angles are 0°. There are three shorter (2.09 Å) and three longer (2.19 Å) Mg–O bond lengths. H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.97 Å. There are two inequivalent O2- sites. In the first O2- site, O2- is bonded to six equivalent Mg2+ atoms to form edge-sharing OMg6 octahedra. In the second O2- site, O2- is bonded in a distorted single-bond geometry to three equivalent Mg2+ and one H1+ atom.