Mn3AlN3 crystallizes in the monoclinic P2_1/m space group. There are three inequivalent Mn sites. In the first Mn site, Mn(1) is bonded in a rectangular see-saw-like geometry to one N(2), one N(3), and two equivalent N(1) atoms. In the second Mn site, Mn(2) is bonded in a rectangular see-saw-like geometry to one N(1), one N(3), and two equivalent N(2) atoms. In the third Mn site, Mn(3) is bonded to one N(1), one N(2), and three equivalent N(3) atoms to form a mixture of corner and edge-sharing MnN5 square pyramids. Al(1) is bonded in a distorted trigonal planar geometry to one N(1), one N(2), and one N(3) atom. There are three inequivalent N sites. In the first N site, N(1) is bonded to one Mn(2), one Mn(3), two equivalent Mn(1), and one Al(1) atom to form NMn4Al trigonal bipyramids that share  a cornercorner with one N(3)Mn5Al octahedra, corners with two equivalent N(1)Mn4Al trigonal bipyramids, corners with two equivalent N(2)Mn4Al trigonal bipyramids, edges with three equivalent N(3)Mn5Al octahedra, and edges with two equivalent N(2)Mn4Al trigonal bipyramids. The corner-sharing octahedral tilt angles are 36°. In the second N site, N(2) is bonded to one Mn(1), one Mn(3), two equivalent Mn(2), and one Al(1) atom to form NMn4Al trigonal bipyramids that share corners with three equivalent N(3)Mn5Al octahedra, corners with two equivalent N(1)Mn4Al trigonal bipyramids, corners with two equivalent N(2)Mn4Al trigonal bipyramids, edges with two equivalent N(3)Mn5Al octahedra, and edges with two equivalent N(1)Mn4Al trigonal bipyramids. The corner-sharing octahedral tilt angles range from 1-38°. In the third N site, N(3) is bonded to one Mn(1), one Mn(2), three equivalent Mn(3), and one Al(1) atom to form NMn5Al octahedra that share corners with two equivalent N(3)Mn5Al octahedra,  a cornercorner with one N(1)Mn4Al trigonal bipyramid, corners with three equivalent N(2)Mn4Al trigonal bipyramids, edges with two equivalent N(3)Mn5Al octahedra, edges with two equivalent N(2)Mn4Al trigonal bipyramids, and edges with three equivalent N(1)Mn4Al trigonal bipyramids. The corner-sharing octahedral tilt angles are 9°.
Mn3AlN3 crystallizes in the monoclinic P2_1/m space group. There are three inequivalent Mn sites. In the first Mn site, Mn(1) is bonded in a rectangular see-saw-like geometry to one N(2), one N(3), and two equivalent N(1) atoms. The Mn(1)-N(2) bond length is 2.06 Å. The Mn(1)-N(3) bond length is 2.09 Å. Both Mn(1)-N(1) bond lengths are 2.01 Å. In the second Mn site, Mn(2) is bonded in a rectangular see-saw-like geometry to one N(1), one N(3), and two equivalent N(2) atoms. The Mn(2)-N(1) bond length is 1.91 Å. The Mn(2)-N(3) bond length is 2.08 Å. Both Mn(2)-N(2) bond lengths are 2.01 Å. In the third Mn site, Mn(3) is bonded to one N(1), one N(2), and three equivalent N(3) atoms to form a mixture of corner and edge-sharing MnN5 square pyramids. The Mn(3)-N(1) bond length is 2.15 Å. The Mn(3)-N(2) bond length is 2.02 Å. There are two shorter (2.00 Å) and one longer (2.22 Å) Mn(3)-N(3) bond length. Al(1) is bonded in a distorted trigonal planar geometry to one N(1), one N(2), and one N(3) atom. The Al(1)-N(1) bond length is 1.87 Å. The Al(1)-N(2) bond length is 1.85 Å. The Al(1)-N(3) bond length is 1.89 Å. There are three inequivalent N sites. In the first N site, N(1) is bonded to one Mn(2), one Mn(3), two equivalent Mn(1), and one Al(1) atom to form NMn4Al trigonal bipyramids that share  a cornercorner with one N(3)Mn5Al octahedra, corners with two equivalent N(1)Mn4Al trigonal bipyramids, corners with two equivalent N(2)Mn4Al trigonal bipyramids, edges with three equivalent N(3)Mn5Al octahedra, and edges with two equivalent N(2)Mn4Al trigonal bipyramids. The corner-sharing octahedral tilt angles are 36°. In the second N site, N(2) is bonded to one Mn(1), one Mn(3), two equivalent Mn(2), and one Al(1) atom to form NMn4Al trigonal bipyramids that share corners with three equivalent N(3)Mn5Al octahedra, corners with two equivalent N(1)Mn4Al trigonal bipyramids, corners with two equivalent N(2)Mn4Al trigonal bipyramids, edges with two equivalent N(3)Mn5Al octahedra, and edges with two equivalent N(1)Mn4Al trigonal bipyramids. The corner-sharing octahedral tilt angles range from 1-38°. In the third N site, N(3) is bonded to one Mn(1), one Mn(2), three equivalent Mn(3), and one Al(1) atom to form NMn5Al octahedra that share corners with two equivalent N(3)Mn5Al octahedra,  a cornercorner with one N(1)Mn4Al trigonal bipyramid, corners with three equivalent N(2)Mn4Al trigonal bipyramids, edges with two equivalent N(3)Mn5Al octahedra, edges with two equivalent N(2)Mn4Al trigonal bipyramids, and edges with three equivalent N(1)Mn4Al trigonal bipyramids. The corner-sharing octahedral tilt angles are 9°.