Materials Data on NdMg(NiH)4 by Materials Project
NdNi4MgH4 crystallizes in the orthorhombic Pmn2_1 space group. The structure is three-dimensional. Mg is bonded in a 3-coordinate geometry to three H atoms. There are one shorter (2.18 Å) and two longer (2.20 Å) Mg–H bond lengths. Nd is bonded in a 7-coordinate geometry to seven H atoms. There are a spread of Nd–H bond distances ranging from 2.36–2.53 Å. There are three inequivalent Ni sites. In the first Ni site, Ni is bonded in a 3-coordinate geometry to three H atoms. There is two shorter (1.65 Å) and one longer (1.70 Å) Ni–H bond length. In the second Ni site, Ni is bonded in a water-like geometry to two H atoms. There is one shorter (1.63 Å) and one longer (1.64 Å) Ni–H bond length. In the third Ni site, Ni is bonded in a water-like geometry to two H atoms. There is one shorter (1.63 Å) and one longer (1.68 Å) Ni–H bond length. There are three inequivalent H sites. In the first H site, H is bonded to one Mg, two equivalent Nd, and two Ni atoms to form distorted HNd2MgNi2 trigonal bipyramids that share corners with three equivalent HNdNi3 tetrahedra, corners with six HNd2MgNi2 trigonal bipyramids, and edges with four HNd2MgNi2 trigonal bipyramids. In the second H site, H is bonded to one Mg, two equivalent Nd, and two Ni atoms to form distorted HNd2MgNi2 trigonal bipyramids that share corners with three equivalent HNdNi3 tetrahedra, corners with six HNd2MgNi2 trigonal bipyramids, and edges with four equivalent HNd2MgNi2 trigonal bipyramids. In the third H site, H is bonded to one Nd and three Ni atoms to form corner-sharing HNdNi3 tetrahedra.