Mg3Ni crystallizes in the orthorhombic Pmm2 space group. There are three inequivalent Mg sites. In the first Mg site, Mg(1) is bonded to four equivalent Ni(1) atoms to form a mixture of distorted corner and edge-sharing MgNi4 cuboctahedra. In the second Mg site, Mg(2) is bonded in a 4-coordinate geometry to four equivalent Ni(1) atoms. In the third Mg site, Mg(3) is bonded in a 2-coordinate geometry to two equivalent Ni(1) atoms. Ni(1) is bonded in a 10-coordinate geometry to two equivalent Mg(3), four equivalent Mg(1), and four equivalent Mg(2) atoms.
Mg3Ni crystallizes in the orthorhombic Pmm2 space group. There are three inequivalent Mg sites. In the first Mg site, Mg(1) is bonded to four equivalent Ni(1) atoms to form a mixture of distorted corner and edge-sharing MgNi4 cuboctahedra. There are two shorter (2.92 Å) and two longer (2.97 Å) Mg(1)-Ni(1) bond lengths. In the second Mg site, Mg(2) is bonded in a 4-coordinate geometry to four equivalent Ni(1) atoms. All Mg(2)-Ni(1) bond lengths are 2.89 Å. In the third Mg site, Mg(3) is bonded in a 2-coordinate geometry to two equivalent Ni(1) atoms. Both Mg(3)-Ni(1) bond lengths are 2.84 Å. Ni(1) is bonded in a 10-coordinate geometry to two equivalent Mg(3), four equivalent Mg(1), and four equivalent Mg(2) atoms.