Materials Data on CsMgH3 by Materials Project

Abstract

CsMgH3 crystallizes in the trigonal R-3m space group. The structure is three-dimensional. there are two inequivalent Cs1+ sites. In the first Cs1+ site, Cs1+ is bonded to twelve H1- atoms to form CsH12 cuboctahedra that share corners with six equivalent CsH12 cuboctahedra, corners with six equivalent MgH6 octahedra, faces with eight equivalent CsH12 cuboctahedra, and faces with six equivalent MgH6 octahedra. The corner-sharing octahedral tilt angles are 7°. There are six shorter (3.13 Å) and six longer (3.21 Å) Cs–H bond lengths. In the second Cs1+ site, Cs1+ is bonded to twelve H1- atoms to form distorted CsH12 cuboctahedra that share corners with nine equivalent CsH12 cuboctahedra, corners with three equivalent MgH6 octahedra, faces with seven CsH12 cuboctahedra, and faces with seven MgH6 octahedra. The corner-sharing octahedral tilt angles are 5°. There are a spread of Cs–H bond distances ranging from 3.16–3.23 Å. There are two inequivalent Mg2+ sites. In the first Mg2+ site, Mg2+ is bonded to six equivalent H1- atoms to form MgH6 octahedra that share corners with six equivalent CsH12 cuboctahedra, faces with six equivalent CsH12 cuboctahedra, and faces with two equivalent MgH6 octahedra. All Mg–H bond lengths are 1.99 Å. In the second Mg2+ site, Mg2+ is bonded to six H1- atoms to form MgH6 octahedra that share corners with three equivalent CsH12 cuboctahedra, corners with three equivalent MgH6 octahedra, faces with seven CsH12 cuboctahedra, and a faceface with one MgH6 octahedra. The corner-sharing octahedral tilt angles are 0°. There are three shorter (2.03 Å) and three longer (2.08 Å) Mg–H bond lengths. There are two inequivalent H1- sites. In the first H1- site, H1- is bonded in a distorted linear geometry to four Cs1+ and two equivalent Mg2+ atoms. In the second H1- site, H1- is bonded in a distorted L-shaped geometry to four Cs1+ and two Mg2+ atoms.