Mg5CuN4 crystallizes in the orthorhombic Pmmn space group. There are two inequivalent Mg sites. In the first Mg site, Mg(1) is bonded in a 4-coordinate geometry to two equivalent N(1) and two equivalent N(2) atoms. In the second Mg site, Mg(2) is bonded to two equivalent N(1) and two equivalent N(2) atoms to form MgN4 tetrahedra that share corners with four equivalent Cu(1)N4 tetrahedra. Cu(1) is bonded to two equivalent N(1) and two equivalent N(2) atoms to form CuN4 tetrahedra that share corners with four equivalent Mg(2)N4 tetrahedra. There are two inequivalent N sites. In the first N site, N(1) is bonded in a 6-coordinate geometry to one Mg(2), four equivalent Mg(1), and one Cu(1) atom. In the second N site, N(2) is bonded to one Mg(2), four equivalent Mg(1), and one Cu(1) atom to form a mixture of distorted corner and edge-sharing NMg5Cu octahedra. The corner-sharing octahedral tilt angles range from 63-67°.
Mg5CuN4 crystallizes in the orthorhombic Pmmn space group. There are two inequivalent Mg sites. In the first Mg site, Mg(1) is bonded in a 4-coordinate geometry to two equivalent N(1) and two equivalent N(2) atoms. There is one shorter (2.10 Å) and one longer (2.43 Å) Mg(1)-N(1) bond length. There is one shorter (2.12 Å) and one longer (2.13 Å) Mg(1)-N(2) bond length. In the second Mg site, Mg(2) is bonded to two equivalent N(1) and two equivalent N(2) atoms to form MgN4 tetrahedra that share corners with four equivalent Cu(1)N4 tetrahedra. Both Mg(2)-N(1) bond lengths are 2.08 Å. Both Mg(2)-N(2) bond lengths are 2.08 Å. Cu(1) is bonded to two equivalent N(1) and two equivalent N(2) atoms to form CuN4 tetrahedra that share corners with four equivalent Mg(2)N4 tetrahedra. Both Cu(1)-N(1) bond lengths are 2.05 Å. Both Cu(1)-N(2) bond lengths are 2.19 Å. There are two inequivalent N sites. In the first N site, N(1) is bonded in a 6-coordinate geometry to one Mg(2), four equivalent Mg(1), and one Cu(1) atom. In the second N site, N(2) is bonded to one Mg(2), four equivalent Mg(1), and one Cu(1) atom to form a mixture of distorted corner and edge-sharing NMg5Cu octahedra. The corner-sharing octahedral tilt angles range from 63-67°.