Materials Data on Rb2MgH4 by Materials Project

Abstract

Rb2MgH4 crystallizes in the orthorhombic Pnma space group. The structure is three-dimensional. there are two inequivalent Rb1+ sites. In the first Rb1+ site, Rb1+ is bonded in a distorted rectangular see-saw-like geometry to four equivalent H1- atoms. All Rb–H bond lengths are 2.88 Å. In the second Rb1+ site, Rb1+ is bonded to six H1- atoms to form distorted RbH6 pentagonal pyramids that share corners with four equivalent MgH4 tetrahedra, edges with two equivalent RbH6 pentagonal pyramids, and an edgeedge with one MgH4 tetrahedra. There are a spread of Rb–H bond distances ranging from 2.77–3.07 Å. Mg2+ is bonded to four H1- atoms to form MgH4 tetrahedra that share corners with four equivalent RbH6 pentagonal pyramids and an edgeedge with one RbH6 pentagonal pyramid. There is two shorter (1.84 Å) and two longer (1.88 Å) Mg–H bond length. There are three inequivalent H1- sites. In the first H1- site, H1- is bonded in a 4-coordinate geometry to three Rb1+ and one Mg2+ atom. In the second H1- site, H1- is bonded in a 1-coordinate geometry to two equivalent Rb1+ and one Mg2+ atom. In the third H1- site, H1- is bonded in a 1-coordinate geometry to two equivalent Rb1+ and one Mg2+ atom.