Rb2MgH4 crystallizes in the orthorhombic Pnma space group. There are two inequivalent Rb sites. In the first Rb site, Rb(1) is bonded in a trigonal non-coplanar geometry to one H(2) and two equivalent H(3) atoms. In the second Rb site, Rb(2) is bonded in a 3-coordinate geometry to one H(1) and two equivalent H(3) atoms. Mg(1) is bonded in a tetrahedral geometry to one H(1), one H(2), and two equivalent H(3) atoms. There are three inequivalent H sites. In the first H site, H(1) is bonded in a bent 120 degrees geometry to one Rb(2) and one Mg(1) atom. In the second H site, H(2) is bonded in a distorted bent 120 degrees geometry to one Rb(1) and one Mg(1) atom. In the third H site, H(3) is bonded in a 3-coordinate geometry to one Rb(1), one Rb(2), and one Mg(1) atom.
Rb2MgH4 crystallizes in the orthorhombic Pnma space group. There are two inequivalent Rb sites. In the first Rb site, Rb(1) is bonded in a trigonal non-coplanar geometry to one H(2) and two equivalent H(3) atoms. The Rb(1)-H(2) bond length is 2.68 Å. Both Rb(1)-H(3) bond lengths are 2.67 Å. In the second Rb site, Rb(2) is bonded in a 3-coordinate geometry to one H(1) and two equivalent H(3) atoms. The Rb(2)-H(1) bond length is 2.65 Å. Both Rb(2)-H(3) bond lengths are 2.80 Å. Mg(1) is bonded in a tetrahedral geometry to one H(1), one H(2), and two equivalent H(3) atoms. The Mg(1)-H(1) bond length is 1.84 Å. The Mg(1)-H(2) bond length is 1.85 Å. Both Mg(1)-H(3) bond lengths are 1.88 Å. There are three inequivalent H sites. In the first H site, H(1) is bonded in a bent 120 degrees geometry to one Rb(2) and one Mg(1) atom. In the second H site, H(2) is bonded in a distorted bent 120 degrees geometry to one Rb(1) and one Mg(1) atom. In the third H site, H(3) is bonded in a 3-coordinate geometry to one Rb(1), one Rb(2), and one Mg(1) atom.