MgMn3CuO8 is beta indium sulfide-derived structured and crystallizes in the monoclinic C2/m space group. Mg(1) is bonded to two equivalent O(2) and four equivalent O(3) atoms to form distorted MgO6 octahedra that share corners with six equivalent Cu(1)O6 octahedra, edges with two equivalent Mn(1)O6 octahedra, and edges with four equivalent Mn(2)O6 octahedra. The corner-sharing octahedral tilt angles are 14°. There are two inequivalent Mn sites. In the first Mn site, Mn(1) is bonded to two equivalent O(1) and four equivalent O(3) atoms to form MnO6 octahedra that share edges with two equivalent Mg(1)O6 octahedra, edges with two equivalent Cu(1)O6 octahedra, and edges with four equivalent Mn(2)O6 octahedra. In the second Mn site, Mn(2) is bonded to two equivalent O(1), two equivalent O(2), and two equivalent O(3) atoms to form MnO6 octahedra that share edges with two equivalent Mg(1)O6 octahedra, edges with two equivalent Mn(1)O6 octahedra, edges with two equivalent Mn(2)O6 octahedra, and edges with two equivalent Cu(1)O6 octahedra. Cu(1) is bonded to two equivalent O(2) and four equivalent O(3) atoms to form CuO6 octahedra that share corners with six equivalent Mg(1)O6 octahedra, edges with two equivalent Mn(1)O6 octahedra, and edges with four equivalent Mn(2)O6 octahedra. The corner-sharing octahedral tilt angles are 14°. There are three inequivalent O sites. In the first O site, O(1) is bonded in a distorted T-shaped geometry to one Mn(1) and two equivalent Mn(2) atoms. In the second O site, O(2) is bonded in a rectangular see-saw-like geometry to one Mg(1), two equivalent Mn(2), and one Cu(1) atom. In the third O site, O(3) is bonded in a rectangular see-saw-like geometry to one Mg(1), one Mn(1), one Mn(2), and one Cu(1) atom.
MgMn3CuO8 is beta indium sulfide-derived structured and crystallizes in the monoclinic C2/m space group. Mg(1) is bonded to two equivalent O(2) and four equivalent O(3) atoms to form distorted MgO6 octahedra that share corners with six equivalent Cu(1)O6 octahedra, edges with two equivalent Mn(1)O6 octahedra, and edges with four equivalent Mn(2)O6 octahedra. The corner-sharing octahedral tilt angles are 14°. Both Mg(1)-O(2) bond lengths are 2.13 Å. All Mg(1)-O(3) bond lengths are 2.14 Å. There are two inequivalent Mn sites. In the first Mn site, Mn(1) is bonded to two equivalent O(1) and four equivalent O(3) atoms to form MnO6 octahedra that share edges with two equivalent Mg(1)O6 octahedra, edges with two equivalent Cu(1)O6 octahedra, and edges with four equivalent Mn(2)O6 octahedra. Both Mn(1)-O(1) bond lengths are 1.96 Å. All Mn(1)-O(3) bond lengths are 1.94 Å. In the second Mn site, Mn(2) is bonded to two equivalent O(1), two equivalent O(2), and two equivalent O(3) atoms to form MnO6 octahedra that share edges with two equivalent Mg(1)O6 octahedra, edges with two equivalent Mn(1)O6 octahedra, edges with two equivalent Mn(2)O6 octahedra, and edges with two equivalent Cu(1)O6 octahedra. Both Mn(2)-O(1) bond lengths are 1.96 Å. Both Mn(2)-O(2) bond lengths are 1.93 Å. Both Mn(2)-O(3) bond lengths are 1.94 Å. Cu(1) is bonded to two equivalent O(2) and four equivalent O(3) atoms to form CuO6 octahedra that share corners with six equivalent Mg(1)O6 octahedra, edges with two equivalent Mn(1)O6 octahedra, and edges with four equivalent Mn(2)O6 octahedra. The corner-sharing octahedral tilt angles are 14°. Both Cu(1)-O(2) bond lengths are 2.12 Å. All Cu(1)-O(3) bond lengths are 2.11 Å. There are three inequivalent O sites. In the first O site, O(1) is bonded in a distorted T-shaped geometry to one Mn(1) and two equivalent Mn(2) atoms. In the second O site, O(2) is bonded in a rectangular see-saw-like geometry to one Mg(1), two equivalent Mn(2), and one Cu(1) atom. In the third O site, O(3) is bonded in a rectangular see-saw-like geometry to one Mg(1), one Mn(1), one Mn(2), and one Cu(1) atom.