MgMn4CuO8 crystallizes in the monoclinic C2/m space group. Mg(1) is bonded to two equivalent O(1) and four equivalent O(2) atoms to form MgO6 octahedra that share corners with six equivalent Cu(1)O6 octahedra, edges with two equivalent Mn(1)O6 octahedra, edges with two equivalent Mn(2)O6 octahedra, and edges with four equivalent Mn(3)O6 octahedra. The corner-sharing octahedral tilt angles range from 12-16°. There are three inequivalent Mn sites. In the first Mn site, Mn(1) is bonded to two equivalent O(3) and four equivalent O(2) atoms to form MnO6 octahedra that share corners with six equivalent Mn(2)O6 octahedra, edges with two equivalent Mg(1)O6 octahedra, edges with two equivalent Cu(1)O6 octahedra, and edges with four equivalent Mn(3)O6 octahedra. The corner-sharing octahedral tilt angles range from 13-16°. In the second Mn site, Mn(2) is bonded to two equivalent O(3) and four equivalent O(2) atoms to form distorted MnO6 octahedra that share corners with six equivalent Mn(1)O6 octahedra, edges with two equivalent Mg(1)O6 octahedra, edges with two equivalent Cu(1)O6 octahedra, and edges with four equivalent Mn(3)O6 octahedra. The corner-sharing octahedral tilt angles range from 13-16°. In the third Mn site, Mn(3) 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, edges with two equivalent Mn(3)O6 octahedra, and edges with two equivalent Cu(1)O6 octahedra. Cu(1) is bonded to two equivalent O(1) and four equivalent O(2) atoms to form CuO6 octahedra that share corners with six equivalent Mg(1)O6 octahedra, edges with two equivalent Mn(1)O6 octahedra, edges with two equivalent Mn(2)O6 octahedra, and edges with four equivalent Mn(3)O6 octahedra. The corner-sharing octahedral tilt angles range from 12-16°. There are three inequivalent O sites. In the first O site, O(1) is bonded in a rectangular see-saw-like geometry to one Mg(1), two equivalent Mn(3), and one Cu(1) atom. In the second O site, O(2) is bonded to one Mg(1), one Mn(1), one Mn(2), one Mn(3), and one Cu(1) atom to form a mixture of corner and edge-sharing OMgMn3Cu square pyramids. In the third O site, O(3) is bonded in a see-saw-like geometry to one Mn(1), one Mn(2), and two equivalent Mn(3) atoms.
MgMn4CuO8 crystallizes in the monoclinic C2/m space group. Mg(1) is bonded to two equivalent O(1) and four equivalent O(2) atoms to form MgO6 octahedra that share corners with six equivalent Cu(1)O6 octahedra, edges with two equivalent Mn(1)O6 octahedra, edges with two equivalent Mn(2)O6 octahedra, and edges with four equivalent Mn(3)O6 octahedra. The corner-sharing octahedral tilt angles range from 12-16°. Both Mg(1)-O(1) bond lengths are 2.24 Å. All Mg(1)-O(2) bond lengths are 2.08 Å. There are three inequivalent Mn sites. In the first Mn site, Mn(1) is bonded to two equivalent O(3) and four equivalent O(2) atoms to form MnO6 octahedra that share corners with six equivalent Mn(2)O6 octahedra, edges with two equivalent Mg(1)O6 octahedra, edges with two equivalent Cu(1)O6 octahedra, and edges with four equivalent Mn(3)O6 octahedra. The corner-sharing octahedral tilt angles range from 13-16°. Both Mn(1)-O(3) bond lengths are 2.18 Å. All Mn(1)-O(2) bond lengths are 2.16 Å. In the second Mn site, Mn(2) is bonded to two equivalent O(3) and four equivalent O(2) atoms to form distorted MnO6 octahedra that share corners with six equivalent Mn(1)O6 octahedra, edges with two equivalent Mg(1)O6 octahedra, edges with two equivalent Cu(1)O6 octahedra, and edges with four equivalent Mn(3)O6 octahedra. The corner-sharing octahedral tilt angles range from 13-16°. Both Mn(2)-O(3) bond lengths are 2.14 Å. All Mn(2)-O(2) bond lengths are 2.21 Å. In the third Mn site, Mn(3) 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, edges with two equivalent Mn(3)O6 octahedra, and edges with two equivalent Cu(1)O6 octahedra. Both Mn(3)-O(1) bond lengths are 1.97 Å. Both Mn(3)-O(2) bond lengths are 1.93 Å. Both Mn(3)-O(3) bond lengths are 1.97 Å. Cu(1) is bonded to two equivalent O(1) and four equivalent O(2) atoms to form CuO6 octahedra that share corners with six equivalent Mg(1)O6 octahedra, edges with two equivalent Mn(1)O6 octahedra, edges with two equivalent Mn(2)O6 octahedra, and edges with four equivalent Mn(3)O6 octahedra. The corner-sharing octahedral tilt angles range from 12-16°. Both Cu(1)-O(1) bond lengths are 2.08 Å. All Cu(1)-O(2) bond lengths are 2.29 Å. There are three inequivalent O sites. In the first O site, O(1) is bonded in a rectangular see-saw-like geometry to one Mg(1), two equivalent Mn(3), and one Cu(1) atom. In the second O site, O(2) is bonded to one Mg(1), one Mn(1), one Mn(2), one Mn(3), and one Cu(1) atom to form a mixture of corner and edge-sharing OMgMn3Cu square pyramids. In the third O site, O(3) is bonded in a see-saw-like geometry to one Mn(1), one Mn(2), and two equivalent Mn(3) atoms.