Mg2Mn3O8 crystallizes in the orthorhombic Cmce space group. Mg(1) is bonded to one O(2), one O(3), and two equivalent O(1) atoms to form MgO4 tetrahedra that share corners with three equivalent Mn(2)O6 octahedra and corners with six equivalent Mn(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 52-64°. There are two inequivalent Mn sites. In the first Mn site, Mn(1) is bonded to two equivalent O(1), two equivalent O(2), and two equivalent O(3) atoms to form MnO6 octahedra that share corners with six equivalent Mg(1)O4 tetrahedra, edges with two equivalent Mn(1)O6 octahedra, and edges with two equivalent Mn(2)O6 octahedra. In the second Mn site, Mn(2) is bonded to two equivalent O(2) and four equivalent O(1) atoms to form MnO6 octahedra that share corners with six equivalent Mg(1)O4 tetrahedra and edges with four equivalent Mn(1)O6 octahedra. There are three inequivalent O sites. In the first O site, O(1) is bonded in a trigonal planar geometry to one Mg(1), one Mn(1), and one Mn(2) atom. In the second O site, O(2) is bonded in a rectangular see-saw-like geometry to one Mg(1), one Mn(2), and two equivalent Mn(1) atoms. In the third O site, O(3) is bonded in a trigonal non-coplanar geometry to one Mg(1) and two equivalent Mn(1) atoms.
Mg2Mn3O8 crystallizes in the orthorhombic Cmce space group. Mg(1) is bonded to one O(2), one O(3), and two equivalent O(1) atoms to form MgO4 tetrahedra that share corners with three equivalent Mn(2)O6 octahedra and corners with six equivalent Mn(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 52-64°. The Mg(1)-O(2) bond length is 2.12 Å. The Mg(1)-O(3) bond length is 1.98 Å. Both Mg(1)-O(1) bond lengths are 1.95 Å. There are two inequivalent Mn sites. In the first Mn site, Mn(1) is bonded to two equivalent O(1), two equivalent O(2), and two equivalent O(3) atoms to form MnO6 octahedra that share corners with six equivalent Mg(1)O4 tetrahedra, edges with two equivalent Mn(1)O6 octahedra, and edges with two equivalent Mn(2)O6 octahedra. Both Mn(1)-O(1) bond lengths are 1.89 Å. Both Mn(1)-O(2) bond lengths are 2.02 Å. Both Mn(1)-O(3) bond lengths are 1.91 Å. In the second Mn site, Mn(2) is bonded to two equivalent O(2) and four equivalent O(1) atoms to form MnO6 octahedra that share corners with six equivalent Mg(1)O4 tetrahedra and edges with four equivalent Mn(1)O6 octahedra. Both Mn(2)-O(2) bond lengths are 1.98 Å. All Mn(2)-O(1) bond lengths are 1.90 Å. There are three inequivalent O sites. In the first O site, O(1) is bonded in a trigonal planar geometry to one Mg(1), one Mn(1), and one Mn(2) atom. In the second O site, O(2) is bonded in a rectangular see-saw-like geometry to one Mg(1), one Mn(2), and two equivalent Mn(1) atoms. In the third O site, O(3) is bonded in a trigonal non-coplanar geometry to one Mg(1) and two equivalent Mn(1) atoms.