MgMn3BiO8 crystallizes in the trigonal R-3m space group. Mg(1) is bonded to six equivalent O(1) atoms to form MgO6 octahedra that share edges with six equivalent Mn(1)O6 octahedra. Mn(1) is bonded to two equivalent O(2) and four equivalent O(1) atoms to form MnO6 octahedra that share edges with two equivalent Mg(1)O6 octahedra and edges with four equivalent Mn(1)O6 octahedra. Bi(1) is bonded in a 6-coordinate geometry to six equivalent O(1) atoms. There are two inequivalent O sites. In the first O site, O(1) is bonded in a distorted rectangular see-saw-like geometry to one Mg(1), two equivalent Mn(1), and one Bi(1) atom. In the second O site, O(2) is bonded in a distorted trigonal non-coplanar geometry to three equivalent Mn(1) atoms.
MgMn3BiO8 crystallizes in the trigonal R-3m space group. Mg(1) is bonded to six equivalent O(1) atoms to form MgO6 octahedra that share edges with six equivalent Mn(1)O6 octahedra. All Mg(1)-O(1) bond lengths are 2.10 Å. Mn(1) is bonded to two equivalent O(2) and four equivalent O(1) atoms to form MnO6 octahedra that share edges with two equivalent Mg(1)O6 octahedra and edges with four equivalent Mn(1)O6 octahedra. Both Mn(1)-O(2) bond lengths are 1.97 Å. All Mn(1)-O(1) bond lengths are 1.99 Å. Bi(1) is bonded in a 6-coordinate geometry to six equivalent O(1) atoms. All Bi(1)-O(1) bond lengths are 2.42 Å. There are two inequivalent O sites. In the first O site, O(1) is bonded in a distorted rectangular see-saw-like geometry to one Mg(1), two equivalent Mn(1), and one Bi(1) atom. In the second O site, O(2) is bonded in a distorted trigonal non-coplanar geometry to three equivalent Mn(1) atoms.