MgFeO2 crystallizes in the monoclinic C2/m space group. There are two inequivalent Mg sites. In the first Mg site, Mg(1) is bonded in a 5-coordinate geometry to one O(1), two equivalent O(3), and two equivalent O(4) atoms. In the second Mg site, Mg(2) is bonded in a distorted rectangular see-saw-like geometry to one O(3), one O(4), and two equivalent O(2) atoms. There are two inequivalent Fe sites. In the first Fe site, Fe(1) is bonded in a 3-coordinate geometry to one O(2) and two equivalent O(1) atoms. In the second Fe site, Fe(2) is bonded to one O(1), two equivalent O(2), and three equivalent O(4) atoms to form distorted edge-sharing FeO6 octahedra. There are four inequivalent O sites. In the first O site, O(1) is bonded to one Mg(1), one Fe(2), and two equivalent Fe(1) atoms to form distorted corner-sharing OMgFe3 tetrahedra. In the second O site, O(2) is bonded in a 5-coordinate geometry to two equivalent Mg(2), one Fe(1), and two equivalent Fe(2) atoms. In the third O site, O(3) is bonded in a 3-coordinate geometry to one Mg(2) and two equivalent Mg(1) atoms. In the fourth O site, O(4) is bonded in a 6-coordinate geometry to one Mg(2), two equivalent Mg(1), and three equivalent Fe(2) atoms.
MgFeO2 crystallizes in the monoclinic C2/m space group. There are two inequivalent Mg sites. In the first Mg site, Mg(1) is bonded in a 5-coordinate geometry to one O(1), two equivalent O(3), and two equivalent O(4) atoms. The Mg(1)-O(1) bond length is 1.97 Å. Both Mg(1)-O(3) bond lengths are 2.03 Å. Both Mg(1)-O(4) bond lengths are 2.35 Å. In the second Mg site, Mg(2) is bonded in a distorted rectangular see-saw-like geometry to one O(3), one O(4), and two equivalent O(2) atoms. The Mg(2)-O(3) bond length is 1.90 Å. The Mg(2)-O(4) bond length is 2.03 Å. Both Mg(2)-O(2) bond lengths are 2.03 Å. There are two inequivalent Fe sites. In the first Fe site, Fe(1) is bonded in a 3-coordinate geometry to one O(2) and two equivalent O(1) atoms. The Fe(1)-O(2) bond length is 2.03 Å. Both Fe(1)-O(1) bond lengths are 2.00 Å. In the second Fe site, Fe(2) is bonded to one O(1), two equivalent O(2), and three equivalent O(4) atoms to form distorted edge-sharing FeO6 octahedra. The Fe(2)-O(1) bond length is 2.13 Å. Both Fe(2)-O(2) bond lengths are 2.25 Å. There are two shorter (2.18 Å) and one longer (2.34 Å) Fe(2)-O(4) bond length. There are four inequivalent O sites. In the first O site, O(1) is bonded to one Mg(1), one Fe(2), and two equivalent Fe(1) atoms to form distorted corner-sharing OMgFe3 tetrahedra. In the second O site, O(2) is bonded in a 5-coordinate geometry to two equivalent Mg(2), one Fe(1), and two equivalent Fe(2) atoms. In the third O site, O(3) is bonded in a 3-coordinate geometry to one Mg(2) and two equivalent Mg(1) atoms. In the fourth O site, O(4) is bonded in a 6-coordinate geometry to one Mg(2), two equivalent Mg(1), and three equivalent Fe(2) atoms.