MgNdNi4H7 crystallizes in the cubic F-43m space group. Mg(1) is bonded to six equivalent H(1) atoms to form MgH6 octahedra that share corners with twelve equivalent Ni(1)H4 tetrahedra and faces with four equivalent Nd(1)H12 cuboctahedra. Nd(1) is bonded to twelve equivalent H(1) atoms to form NdH12 cuboctahedra that share corners with twelve equivalent Nd(1)H12 cuboctahedra, edges with twelve equivalent Ni(1)H4 tetrahedra, and faces with four equivalent Mg(1)H6 octahedra. Ni(1) is bonded to one H(2) and three equivalent H(1) atoms to form NiH4 tetrahedra that share corners with three equivalent Mg(1)H6 octahedra, corners with six equivalent Ni(1)H4 tetrahedra, and edges with three equivalent Nd(1)H12 cuboctahedra. The corner-sharing octahedral tilt angles are 57°. There are two inequivalent H sites. In the first H site, H(1) is bonded in a distorted trigonal planar geometry to one Mg(1), two equivalent Nd(1), and two equivalent Ni(1) atoms. In the second H site, H(2) is bonded in a tetrahedral geometry to four equivalent Ni(1) atoms.
MgNdNi4H7 crystallizes in the cubic F-43m space group. Mg(1) is bonded to six equivalent H(1) atoms to form MgH6 octahedra that share corners with twelve equivalent Ni(1)H4 tetrahedra and faces with four equivalent Nd(1)H12 cuboctahedra. All Mg(1)-H(1) bond lengths are 1.98 Å. Nd(1) is bonded to twelve equivalent H(1) atoms to form NdH12 cuboctahedra that share corners with twelve equivalent Nd(1)H12 cuboctahedra, edges with twelve equivalent Ni(1)H4 tetrahedra, and faces with four equivalent Mg(1)H6 octahedra. All Nd(1)-H(1) bond lengths are 2.71 Å. Ni(1) is bonded to one H(2) and three equivalent H(1) atoms to form NiH4 tetrahedra that share corners with three equivalent Mg(1)H6 octahedra, corners with six equivalent Ni(1)H4 tetrahedra, and edges with three equivalent Nd(1)H12 cuboctahedra. The corner-sharing octahedral tilt angles are 57°. The Ni(1)-H(2) bond length is 1.64 Å. All Ni(1)-H(1) bond lengths are 1.63 Å. There are two inequivalent H sites. In the first H site, H(1) is bonded in a distorted trigonal planar geometry to one Mg(1), two equivalent Nd(1), and two equivalent Ni(1) atoms. In the second H site, H(2) is bonded in a tetrahedral geometry to four equivalent Ni(1) atoms.