Mg2Fe3O8 is beta indium sulfide-derived structured and crystallizes in the monoclinic C2/m space group. Mg(1) is bonded in a 6-coordinate geometry to one O(1), one O(2), and four equivalent O(3) atoms. There are two inequivalent Fe sites. In the first Fe site, Fe(1) is bonded to two equivalent O(2) and four equivalent O(3) atoms to form edge-sharing FeO6 octahedra. In the second Fe site, Fe(2) is bonded to two equivalent O(1), two equivalent O(2), and two equivalent O(3) atoms to form edge-sharing FeO6 octahedra. There are three inequivalent O sites. In the first O site, O(1) is bonded in a distorted trigonal planar geometry to one Mg(1) and two equivalent Fe(2) atoms. In the second O site, O(2) is bonded in a rectangular see-saw-like geometry to one Mg(1), one Fe(1), and two equivalent Fe(2) atoms. In the third O site, O(3) is bonded to two equivalent Mg(1), one Fe(1), and one Fe(2) atom to form a mixture of distorted corner and edge-sharing OMg2Fe2 tetrahedra.
Mg2Fe3O8 is beta indium sulfide-derived structured and crystallizes in the monoclinic C2/m space group. Mg(1) is bonded in a 6-coordinate geometry to one O(1), one O(2), and four equivalent O(3) atoms. The Mg(1)-O(1) bond length is 2.10 Å. The Mg(1)-O(2) bond length is 2.16 Å. There are two shorter (2.09 Å) and two longer (2.23 Å) Mg(1)-O(3) bond lengths. There are two inequivalent Fe sites. In the first Fe site, Fe(1) is bonded to two equivalent O(2) and four equivalent O(3) atoms to form edge-sharing FeO6 octahedra. Both Fe(1)-O(2) bond lengths are 2.00 Å. All Fe(1)-O(3) bond lengths are 1.97 Å. In the second Fe site, Fe(2) is bonded to two equivalent O(1), two equivalent O(2), and two equivalent O(3) atoms to form edge-sharing FeO6 octahedra. Both Fe(2)-O(1) bond lengths are 1.88 Å. Both Fe(2)-O(2) bond lengths are 1.98 Å. Both Fe(2)-O(3) bond lengths are 1.90 Å. There are three inequivalent O sites. In the first O site, O(1) is bonded in a distorted trigonal planar geometry to one Mg(1) and two equivalent Fe(2) atoms. In the second O site, O(2) is bonded in a rectangular see-saw-like geometry to one Mg(1), one Fe(1), and two equivalent Fe(2) atoms. In the third O site, O(3) is bonded to two equivalent Mg(1), one Fe(1), and one Fe(2) atom to form a mixture of distorted corner and edge-sharing OMg2Fe2 tetrahedra.