MgMn(CoO3)2 crystallizes in the monoclinic Cm space group. Mg(1) is bonded to one O(2), one O(5), two equivalent O(1), and two equivalent O(6) atoms to form MgO6 octahedra that share  a cornercorner with one Mn(1)O6 octahedra,  a cornercorner with one Co(2)O6 octahedra, corners with four equivalent Co(1)O6 octahedra, edges with two equivalent Mg(1)O6 octahedra, edges with two equivalent Mn(1)O6 octahedra, edges with two equivalent Co(1)O6 octahedra, and edges with two equivalent Co(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 3-19°. Mn(1) is bonded to one O(1), one O(5), two equivalent O(2), and two equivalent O(4) atoms to form MnO6 octahedra that share  a cornercorner with one Mg(1)O6 octahedra, edges with two equivalent Mg(1)O6 octahedra, edges with two equivalent Mn(1)O6 octahedra, edges with two equivalent Co(1)O6 octahedra, and edges with two equivalent Co(2)O6 octahedra. The corner-sharing octahedral tilt angles are 18°. There are two inequivalent Co sites. In the first Co site, Co(1) is bonded to one O(3), one O(4), two equivalent O(1), and two equivalent O(6) atoms to form CoO6 octahedra that share corners with four equivalent Mg(1)O6 octahedra, edges with two equivalent Mg(1)O6 octahedra, edges with two equivalent Mn(1)O6 octahedra, edges with two equivalent Co(1)O6 octahedra, and edges with two equivalent Co(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 3-9°. In the second Co site, Co(2) is bonded to one O(2), one O(6), two equivalent O(3), and two equivalent O(5) atoms to form CoO6 octahedra that share  a cornercorner with one Mg(1)O6 octahedra, edges with two equivalent Mg(1)O6 octahedra, edges with two equivalent Mn(1)O6 octahedra, edges with two equivalent Co(1)O6 octahedra, and edges with two equivalent Co(2)O6 octahedra. The corner-sharing octahedral tilt angles are 19°. There are six inequivalent O sites. In the first O site, O(1) is bonded to two equivalent Mg(1), one Mn(1), and two equivalent Co(1) atoms to form OMg2MnCo2 square pyramids that share corners with four equivalent O(6)Mg2Co3 square pyramids, edges with two equivalent O(6)Mg2Co3 square pyramids, and edges with two equivalent O(1)Mg2MnCo2 square pyramids. In the second O site, O(2) is bonded in a distorted rectangular see-saw-like geometry to one Mg(1), two equivalent Mn(1), and one Co(2) atom. In the third O site, O(3) is bonded in a distorted trigonal non-coplanar geometry to one Co(1) and two equivalent Co(2) atoms. In the fourth O site, O(4) is bonded in a distorted trigonal non-coplanar geometry to two equivalent Mn(1) and one Co(1) atom. In the fifth O site, O(5) is bonded in a rectangular see-saw-like geometry to one Mg(1), one Mn(1), and two equivalent Co(2) atoms. In the sixth O site, O(6) is bonded to two equivalent Mg(1), one Co(2), and two equivalent Co(1) atoms to form OMg2Co3 square pyramids that share corners with four equivalent O(1)Mg2MnCo2 square pyramids, edges with two equivalent O(6)Mg2Co3 square pyramids, and edges with two equivalent O(1)Mg2MnCo2 square pyramids.
MgMn(CoO3)2 crystallizes in the monoclinic Cm space group. Mg(1) is bonded to one O(2), one O(5), two equivalent O(1), and two equivalent O(6) atoms to form MgO6 octahedra that share  a cornercorner with one Mn(1)O6 octahedra,  a cornercorner with one Co(2)O6 octahedra, corners with four equivalent Co(1)O6 octahedra, edges with two equivalent Mg(1)O6 octahedra, edges with two equivalent Mn(1)O6 octahedra, edges with two equivalent Co(1)O6 octahedra, and edges with two equivalent Co(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 3-19°. The Mg(1)-O(2) bond length is 2.12 Å. The Mg(1)-O(5) bond length is 2.21 Å. Both Mg(1)-O(1) bond lengths are 2.13 Å. Both Mg(1)-O(6) bond lengths are 2.06 Å. Mn(1) is bonded to one O(1), one O(5), two equivalent O(2), and two equivalent O(4) atoms to form MnO6 octahedra that share  a cornercorner with one Mg(1)O6 octahedra, edges with two equivalent Mg(1)O6 octahedra, edges with two equivalent Mn(1)O6 octahedra, edges with two equivalent Co(1)O6 octahedra, and edges with two equivalent Co(2)O6 octahedra. The corner-sharing octahedral tilt angles are 18°. The Mn(1)-O(1) bond length is 1.95 Å. The Mn(1)-O(5) bond length is 1.95 Å. Both Mn(1)-O(2) bond lengths are 1.94 Å. Both Mn(1)-O(4) bond lengths are 1.95 Å. There are two inequivalent Co sites. In the first Co site, Co(1) is bonded to one O(3), one O(4), two equivalent O(1), and two equivalent O(6) atoms to form CoO6 octahedra that share corners with four equivalent Mg(1)O6 octahedra, edges with two equivalent Mg(1)O6 octahedra, edges with two equivalent Mn(1)O6 octahedra, edges with two equivalent Co(1)O6 octahedra, and edges with two equivalent Co(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 3-9°. The Co(1)-O(3) bond length is 1.87 Å. The Co(1)-O(4) bond length is 1.92 Å. Both Co(1)-O(1) bond lengths are 2.10 Å. Both Co(1)-O(6) bond lengths are 2.05 Å. In the second Co site, Co(2) is bonded to one O(2), one O(6), two equivalent O(3), and two equivalent O(5) atoms to form CoO6 octahedra that share  a cornercorner with one Mg(1)O6 octahedra, edges with two equivalent Mg(1)O6 octahedra, edges with two equivalent Mn(1)O6 octahedra, edges with two equivalent Co(1)O6 octahedra, and edges with two equivalent Co(2)O6 octahedra. The corner-sharing octahedral tilt angles are 19°. The Co(2)-O(2) bond length is 2.09 Å. The Co(2)-O(6) bond length is 2.11 Å. Both Co(2)-O(3) bond lengths are 1.91 Å. Both Co(2)-O(5) bond lengths are 1.98 Å. There are six inequivalent O sites. In the first O site, O(1) is bonded to two equivalent Mg(1), one Mn(1), and two equivalent Co(1) atoms to form OMg2MnCo2 square pyramids that share corners with four equivalent O(6)Mg2Co3 square pyramids, edges with two equivalent O(6)Mg2Co3 square pyramids, and edges with two equivalent O(1)Mg2MnCo2 square pyramids. In the second O site, O(2) is bonded in a distorted rectangular see-saw-like geometry to one Mg(1), two equivalent Mn(1), and one Co(2) atom. In the third O site, O(3) is bonded in a distorted trigonal non-coplanar geometry to one Co(1) and two equivalent Co(2) atoms. In the fourth O site, O(4) is bonded in a distorted trigonal non-coplanar geometry to two equivalent Mn(1) and one Co(1) atom. In the fifth O site, O(5) is bonded in a rectangular see-saw-like geometry to one Mg(1), one Mn(1), and two equivalent Co(2) atoms. In the sixth O site, O(6) is bonded to two equivalent Mg(1), one Co(2), and two equivalent Co(1) atoms to form OMg2Co3 square pyramids that share corners with four equivalent O(1)Mg2MnCo2 square pyramids, edges with two equivalent O(6)Mg2Co3 square pyramids, and edges with two equivalent O(1)Mg2MnCo2 square pyramids.