Mg5CoN4 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 Co(1)N4 tetrahedra. Co(1) is bonded to two equivalent N(1) and two equivalent N(2) atoms to form CoN4 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 Co(1) atom. In the second N site, N(2) is bonded to one Mg(2), four equivalent Mg(1), and one Co(1) atom to form a mixture of distorted corner and edge-sharing NMg5Co octahedra. The corner-sharing octahedral tilt angles range from 64-65°.
Mg5CoN4 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 (2.11 Å) and one longer (2.36 Å) Mg(1)-N(1) bond length. There is one shorter (2.14 Å) and one longer (2.16 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 Co(1)N4 tetrahedra. Both Mg(2)-N(1) bond lengths are 2.08 Å. Both Mg(2)-N(2) bond lengths are 2.10 Å. Co(1) is bonded to two equivalent N(1) and two equivalent N(2) atoms to form CoN4 tetrahedra that share corners with four equivalent Mg(2)N4 tetrahedra. Both Co(1)-N(1) bond lengths are 2.04 Å. Both Co(1)-N(2) bond lengths are 2.09 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 Co(1) atom. In the second N site, N(2) is bonded to one Mg(2), four equivalent Mg(1), and one Co(1) atom to form a mixture of distorted corner and edge-sharing NMg5Co octahedra. The corner-sharing octahedral tilt angles range from 64-65°.