Mg3Sc2N4 crystallizes in the monoclinic C2/c space group. There are two inequivalent Mg sites. In the first Mg site, Mg(1) is bonded to two equivalent N(2) and three equivalent N(1) atoms to form a mixture of distorted corner and edge-sharing MgN5 trigonal bipyramids. In the second Mg site, Mg(2) is bonded in a 4-coordinate geometry to two equivalent N(1) and two equivalent N(2) atoms. Sc(1) is bonded in a 5-coordinate geometry to two equivalent N(1) and three equivalent N(2) atoms. There are two inequivalent N sites. In the first N site, N(1) is bonded to one Mg(2), three equivalent Mg(1), and two equivalent Sc(1) atoms to form distorted NMg4Sc2 octahedra that share corners with three equivalent N(1)Mg4Sc2 octahedra, corners with seven equivalent N(2)Mg3Sc3 octahedra, edges with two equivalent N(2)Mg3Sc3 octahedra, edges with three equivalent N(1)Mg4Sc2 octahedra, and  a faceface with one N(2)Mg3Sc3 octahedra. The corner-sharing octahedral tilt angles range from 30-70°. In the second N site, N(2) is bonded to one Mg(2), two equivalent Mg(1), and three equivalent Sc(1) atoms to form distorted NMg3Sc3 octahedra that share corners with three equivalent N(2)Mg3Sc3 octahedra, corners with seven equivalent N(1)Mg4Sc2 octahedra, edges with two equivalent N(1)Mg4Sc2 octahedra, edges with three equivalent N(2)Mg3Sc3 octahedra, and  a faceface with one N(1)Mg4Sc2 octahedra. The corner-sharing octahedral tilt angles range from 30-70°.
Mg3Sc2N4 crystallizes in the monoclinic C2/c space group. There are two inequivalent Mg sites. In the first Mg site, Mg(1) is bonded to two equivalent N(2) and three equivalent N(1) atoms to form a mixture of distorted corner and edge-sharing MgN5 trigonal bipyramids. There is one shorter (2.28 Å) and one longer (2.34 Å) Mg(1)-N(2) bond length. There are a spread of Mg(1)-N(1) bond distances ranging from 2.17-2.27 Å. In the second Mg site, Mg(2) is bonded in a 4-coordinate geometry to two equivalent N(1) and two equivalent N(2) atoms. Both Mg(2)-N(1) bond lengths are 2.07 Å. Both Mg(2)-N(2) bond lengths are 2.12 Å. Sc(1) is bonded in a 5-coordinate geometry to two equivalent N(1) and three equivalent N(2) atoms. There is one shorter (2.15 Å) and one longer (2.28 Å) Sc(1)-N(1) bond length. There are a spread of Sc(1)-N(2) bond distances ranging from 2.13-2.40 Å. There are two inequivalent N sites. In the first N site, N(1) is bonded to one Mg(2), three equivalent Mg(1), and two equivalent Sc(1) atoms to form distorted NMg4Sc2 octahedra that share corners with three equivalent N(1)Mg4Sc2 octahedra, corners with seven equivalent N(2)Mg3Sc3 octahedra, edges with two equivalent N(2)Mg3Sc3 octahedra, edges with three equivalent N(1)Mg4Sc2 octahedra, and  a faceface with one N(2)Mg3Sc3 octahedra. The corner-sharing octahedral tilt angles range from 30-70°. In the second N site, N(2) is bonded to one Mg(2), two equivalent Mg(1), and three equivalent Sc(1) atoms to form distorted NMg3Sc3 octahedra that share corners with three equivalent N(2)Mg3Sc3 octahedra, corners with seven equivalent N(1)Mg4Sc2 octahedra, edges with two equivalent N(1)Mg4Sc2 octahedra, edges with three equivalent N(2)Mg3Sc3 octahedra, and  a faceface with one N(1)Mg4Sc2 octahedra. The corner-sharing octahedral tilt angles range from 30-70°.