Materials Data on MgH3 by Materials Project
MgH3 is alpha bismuth trifluoride structured and crystallizes in the cubic Fm-3m space group. The structure is three-dimensional. Mg is bonded in a body-centered cubic geometry to fourteen H atoms. There are eight shorter (2.04 Å) and six longer (2.35 Å) Mg–H bond lengths. There are two inequivalent H sites. In the first H site, H is bonded to six equivalent Mg atoms to form HMg6 octahedra that share corners with six equivalent HMg6 octahedra, corners with twenty-four equivalent HMg4 tetrahedra, edges with twelve equivalent HMg6 octahedra, and faces with eight equivalent HMg4 tetrahedra. The corner-sharing octahedral tilt angles are 0°. In the second H site, H is bonded to four equivalent Mg atoms to form HMg4 tetrahedra that share corners with twelve equivalent HMg6 octahedra, corners with sixteen equivalent HMg4 tetrahedra, edges with six equivalent HMg4 tetrahedra, and faces with four equivalent HMg6 octahedra. The corner-sharing octahedral tilt angles are 55°.