Mg2NiH4 crystallizes in the monoclinic C2/c space group. There are three inequivalent Mg sites. In the first Mg site, Mg(1) is bonded in a 7-coordinate geometry to two equivalent H(2), two equivalent H(4), and three equivalent H(1) atoms. In the second Mg site, Mg(2) is bonded in a 4-coordinate geometry to two equivalent H(3) and two equivalent H(4) atoms. In the third Mg site, Mg(3) is bonded in a 6-coordinate geometry to two equivalent H(2) and four equivalent H(3) atoms. Ni(1) is bonded in a tetrahedral geometry to one H(1), one H(2), one H(3), and one H(4) atom. There are four inequivalent H sites. In the first H site, H(3) is bonded in a distorted see-saw-like geometry to one Mg(2), two equivalent Mg(3), and one Ni(1) atom. In the second H site, H(4) is bonded in a 4-coordinate geometry to one Mg(2), two equivalent Mg(1), and one Ni(1) atom. In the third H site, H(1) is bonded in a distorted see-saw-like geometry to three equivalent Mg(1) and one Ni(1) atom. In the fourth H site, H(2) is bonded in a distorted rectangular see-saw-like geometry to one Mg(3), two equivalent Mg(1), and one Ni(1) atom.
Mg2NiH4 crystallizes in the monoclinic C2/c space group. There are three inequivalent Mg sites. In the first Mg site, Mg(1) is bonded in a 7-coordinate geometry to two equivalent H(2), two equivalent H(4), and three equivalent H(1) atoms. There is one shorter (2.06 Å) and one longer (2.32 Å) Mg(1)-H(2) bond length. There is one shorter (2.14 Å) and one longer (2.20 Å) Mg(1)-H(4) bond length. There are a spread of Mg(1)-H(1) bond distances ranging from 2.09-2.21 Å. In the second Mg site, Mg(2) is bonded in a 4-coordinate geometry to two equivalent H(3) and two equivalent H(4) atoms. Both Mg(2)-H(3) bond lengths are 2.16 Å. Both Mg(2)-H(4) bond lengths are 2.15 Å. In the third Mg site, Mg(3) is bonded in a 6-coordinate geometry to two equivalent H(2) and four equivalent H(3) atoms. Both Mg(3)-H(2) bond lengths are 2.07 Å. There are two shorter (2.00 Å) and two longer (2.22 Å) Mg(3)-H(3) bond lengths. Ni(1) is bonded in a tetrahedral geometry to one H(1), one H(2), one H(3), and one H(4) atom. The Ni(1)-H(1) bond length is 1.55 Å. The Ni(1)-H(2) bond length is 1.54 Å. The Ni(1)-H(3) bond length is 1.54 Å. The Ni(1)-H(4) bond length is 1.53 Å. There are four inequivalent H sites. In the first H site, H(3) is bonded in a distorted see-saw-like geometry to one Mg(2), two equivalent Mg(3), and one Ni(1) atom. In the second H site, H(4) is bonded in a 4-coordinate geometry to one Mg(2), two equivalent Mg(1), and one Ni(1) atom. In the third H site, H(1) is bonded in a distorted see-saw-like geometry to three equivalent Mg(1) and one Ni(1) atom. In the fourth H site, H(2) is bonded in a distorted rectangular see-saw-like geometry to one Mg(3), two equivalent Mg(1), and one Ni(1) atom.