MgMn2(FeO2)4 crystallizes in the triclinic P-1 space group. Mg(1) is bonded to two equivalent O(2), two equivalent O(3), and two equivalent O(4) atoms to form MgO6 octahedra that share corners with six equivalent Fe(1)O6 octahedra, edges with two equivalent Fe(2)O6 octahedra, edges with two equivalent Fe(3)O6 octahedra, and edges with two equivalent Fe(4)O6 octahedra. The corner-sharing octahedral tilt angles range from 5-17°. Mn(1) is bonded in a 5-coordinate geometry to one O(1), one O(2), one O(3), and two equivalent O(4) atoms. There are four inequivalent Fe sites. In the first Fe site, Fe(1) is bonded to two equivalent O(2), two equivalent O(3), and two equivalent O(4) atoms to form distorted FeO6 octahedra that share corners with six equivalent Mg(1)O6 octahedra, edges with two equivalent Fe(2)O6 octahedra, edges with two equivalent Fe(3)O6 octahedra, and edges with two equivalent Fe(4)O6 octahedra. The corner-sharing octahedral tilt angles range from 5-17°. In the second Fe site, Fe(2) is bonded to two equivalent O(1), two equivalent O(3), and two equivalent O(4) atoms to form FeO6 octahedra that share edges with two equivalent Mg(1)O6 octahedra, edges with two equivalent Fe(1)O6 octahedra, edges with two equivalent Fe(3)O6 octahedra, and edges with two equivalent Fe(4)O6 octahedra. In the third Fe site, Fe(3) is bonded to two equivalent O(1), two equivalent O(2), and two equivalent O(3) atoms to form FeO6 octahedra that share edges with two equivalent Mg(1)O6 octahedra, edges with two equivalent Fe(1)O6 octahedra, edges with two equivalent Fe(2)O6 octahedra, and edges with two equivalent Fe(4)O6 octahedra. In the fourth Fe site, Fe(4) is bonded to two equivalent O(1), two equivalent O(2), and two equivalent O(4) atoms to form FeO6 octahedra that share edges with two equivalent Mg(1)O6 octahedra, edges with two equivalent Fe(1)O6 octahedra, edges with two equivalent Fe(2)O6 octahedra, and edges with two equivalent Fe(3)O6 octahedra. There are four inequivalent O sites. In the first O site, O(1) is bonded to one Mn(1), one Fe(2), one Fe(3), and one Fe(4) atom to form OMnFe3 trigonal pyramids that share corners with three equivalent O(2)MgMnFe3 square pyramids, corners with three equivalent O(3)MgMnFe3 trigonal bipyramids, corners with three equivalent O(1)MnFe3 trigonal pyramids,  an edgeedge with one O(2)MgMnFe3 square pyramid, and  an edgeedge with one O(3)MgMnFe3 trigonal bipyramid. In the second O site, O(2) is bonded to one Mg(1), one Mn(1), one Fe(1), one Fe(3), and one Fe(4) atom to form OMgMnFe3 square pyramids that share corners with four equivalent O(2)MgMnFe3 square pyramids,  a cornercorner with one O(3)MgMnFe3 trigonal bipyramid, corners with three equivalent O(1)MnFe3 trigonal pyramids, edges with three equivalent O(3)MgMnFe3 trigonal bipyramids, and  an edgeedge with one O(1)MnFe3 trigonal pyramid. In the third O site, O(3) is bonded to one Mg(1), one Mn(1), one Fe(1), one Fe(2), and one Fe(3) atom to form distorted OMgMnFe3 trigonal bipyramids that share  a cornercorner with one O(2)MgMnFe3 square pyramid, corners with four equivalent O(3)MgMnFe3 trigonal bipyramids, corners with three equivalent O(1)MnFe3 trigonal pyramids, edges with three equivalent O(2)MgMnFe3 square pyramids, and  an edgeedge with one O(1)MnFe3 trigonal pyramid. In the fourth O site, O(4) is bonded in a 6-coordinate geometry to one Mg(1), two equivalent Mn(1), one Fe(1), one Fe(2), and one Fe(4) atom.
MgMn2(FeO2)4 crystallizes in the triclinic P-1 space group. Mg(1) is bonded to two equivalent O(2), two equivalent O(3), and two equivalent O(4) atoms to form MgO6 octahedra that share corners with six equivalent Fe(1)O6 octahedra, edges with two equivalent Fe(2)O6 octahedra, edges with two equivalent Fe(3)O6 octahedra, and edges with two equivalent Fe(4)O6 octahedra. The corner-sharing octahedral tilt angles range from 5-17°. Both Mg(1)-O(2) bond lengths are 2.12 Å. Both Mg(1)-O(3) bond lengths are 2.10 Å. Both Mg(1)-O(4) bond lengths are 2.20 Å. Mn(1) is bonded in a 5-coordinate geometry to one O(1), one O(2), one O(3), and two equivalent O(4) atoms. The Mn(1)-O(1) bond length is 2.00 Å. The Mn(1)-O(2) bond length is 2.22 Å. The Mn(1)-O(3) bond length is 2.20 Å. There is one shorter (2.18 Å) and one longer (2.66 Å) Mn(1)-O(4) bond length. There are four inequivalent Fe sites. In the first Fe site, Fe(1) is bonded to two equivalent O(2), two equivalent O(3), and two equivalent O(4) atoms to form distorted FeO6 octahedra that share corners with six equivalent Mg(1)O6 octahedra, edges with two equivalent Fe(2)O6 octahedra, edges with two equivalent Fe(3)O6 octahedra, and edges with two equivalent Fe(4)O6 octahedra. The corner-sharing octahedral tilt angles range from 5-17°. Both Fe(1)-O(2) bond lengths are 2.07 Å. Both Fe(1)-O(3) bond lengths are 2.64 Å. Both Fe(1)-O(4) bond lengths are 2.26 Å. In the second Fe site, Fe(2) is bonded to two equivalent O(1), two equivalent O(3), and two equivalent O(4) atoms to form FeO6 octahedra that share edges with two equivalent Mg(1)O6 octahedra, edges with two equivalent Fe(1)O6 octahedra, edges with two equivalent Fe(3)O6 octahedra, and edges with two equivalent Fe(4)O6 octahedra. Both Fe(2)-O(1) bond lengths are 2.01 Å. Both Fe(2)-O(3) bond lengths are 2.09 Å. Both Fe(2)-O(4) bond lengths are 2.10 Å. In the third Fe site, Fe(3) is bonded to two equivalent O(1), two equivalent O(2), and two equivalent O(3) atoms to form FeO6 octahedra that share edges with two equivalent Mg(1)O6 octahedra, edges with two equivalent Fe(1)O6 octahedra, edges with two equivalent Fe(2)O6 octahedra, and edges with two equivalent Fe(4)O6 octahedra. Both Fe(3)-O(1) bond lengths are 2.00 Å. Both Fe(3)-O(2) bond lengths are 2.12 Å. Both Fe(3)-O(3) bond lengths are 2.08 Å. In the fourth Fe site, Fe(4) is bonded to two equivalent O(1), two equivalent O(2), and two equivalent O(4) atoms to form FeO6 octahedra that share edges with two equivalent Mg(1)O6 octahedra, edges with two equivalent Fe(1)O6 octahedra, edges with two equivalent Fe(2)O6 octahedra, and edges with two equivalent Fe(3)O6 octahedra. Both Fe(4)-O(1) bond lengths are 2.01 Å. Both Fe(4)-O(2) bond lengths are 2.22 Å. Both Fe(4)-O(4) bond lengths are 2.27 Å. There are four inequivalent O sites. In the first O site, O(1) is bonded to one Mn(1), one Fe(2), one Fe(3), and one Fe(4) atom to form OMnFe3 trigonal pyramids that share corners with three equivalent O(2)MgMnFe3 square pyramids, corners with three equivalent O(3)MgMnFe3 trigonal bipyramids, corners with three equivalent O(1)MnFe3 trigonal pyramids,  an edgeedge with one O(2)MgMnFe3 square pyramid, and  an edgeedge with one O(3)MgMnFe3 trigonal bipyramid. In the second O site, O(2) is bonded to one Mg(1), one Mn(1), one Fe(1), one Fe(3), and one Fe(4) atom to form OMgMnFe3 square pyramids that share corners with four equivalent O(2)MgMnFe3 square pyramids,  a cornercorner with one O(3)MgMnFe3 trigonal bipyramid, corners with three equivalent O(1)MnFe3 trigonal pyramids, edges with three equivalent O(3)MgMnFe3 trigonal bipyramids, and  an edgeedge with one O(1)MnFe3 trigonal pyramid. In the third O site, O(3) is bonded to one Mg(1), one Mn(1), one Fe(1), one Fe(2), and one Fe(3) atom to form distorted OMgMnFe3 trigonal bipyramids that share  a cornercorner with one O(2)MgMnFe3 square pyramid, corners with four equivalent O(3)MgMnFe3 trigonal bipyramids, corners with three equivalent O(1)MnFe3 trigonal pyramids, edges with three equivalent O(2)MgMnFe3 square pyramids, and  an edgeedge with one O(1)MnFe3 trigonal pyramid. In the fourth O site, O(4) is bonded in a 6-coordinate geometry to one Mg(1), two equivalent Mn(1), one Fe(1), one Fe(2), and one Fe(4) atom.