MgFe2(OF)2 crystallizes in the monoclinic Pm space group. Mg(1) is bonded to one O(1), two equivalent O(2), one F(2), and two equivalent F(1) atoms to form MgO3F3 octahedra that share edges with two equivalent Mg(1)O3F3 octahedra and edges with four equivalent Fe(2)O3F3 octahedra. There are two inequivalent Fe sites. In the first Fe site, Fe(1) is bonded in a trigonal planar geometry to one O(1) and two equivalent O(2) atoms. In the second Fe site, Fe(2) is bonded to one O(2), two equivalent O(1), one F(1), and two equivalent F(2) atoms to form FeO3F3 octahedra that share edges with two equivalent Fe(2)O3F3 octahedra and edges with four equivalent Mg(1)O3F3 octahedra. There are two inequivalent O sites. In the first O site, O(1) is bonded to one Mg(1), one Fe(1), and two equivalent Fe(2) atoms to form OMgFe3 tetrahedra that share corners with two equivalent O(2)Mg2Fe3 square pyramids, corners with two equivalent O(1)MgFe3 tetrahedra, and edges with two equivalent O(2)Mg2Fe3 square pyramids. In the second O site, O(2) is bonded to two equivalent Mg(1), one Fe(2), and two equivalent Fe(1) atoms to form OMg2Fe3 square pyramids that share corners with two equivalent O(1)MgFe3 tetrahedra, edges with two equivalent O(2)Mg2Fe3 square pyramids, and edges with two equivalent O(1)MgFe3 tetrahedra. There are two inequivalent F sites. In the first F site, F(1) is bonded in a distorted trigonal non-coplanar geometry to two equivalent Mg(1) and one Fe(2) atom. In the second F site, F(2) is bonded in a distorted trigonal non-coplanar geometry to one Mg(1) and two equivalent Fe(2) atoms.
MgFe2(OF)2 crystallizes in the monoclinic Pm space group. Mg(1) is bonded to one O(1), two equivalent O(2), one F(2), and two equivalent F(1) atoms to form MgO3F3 octahedra that share edges with two equivalent Mg(1)O3F3 octahedra and edges with four equivalent Fe(2)O3F3 octahedra. The Mg(1)-O(1) bond length is 2.03 Å. Both Mg(1)-O(2) bond lengths are 2.25 Å. The Mg(1)-F(2) bond length is 2.03 Å. Both Mg(1)-F(1) bond lengths are 2.02 Å. There are two inequivalent Fe sites. In the first Fe site, Fe(1) is bonded in a trigonal planar geometry to one O(1) and two equivalent O(2) atoms. The Fe(1)-O(1) bond length is 1.91 Å. Both Fe(1)-O(2) bond lengths are 2.01 Å. In the second Fe site, Fe(2) is bonded to one O(2), two equivalent O(1), one F(1), and two equivalent F(2) atoms to form FeO3F3 octahedra that share edges with two equivalent Fe(2)O3F3 octahedra and edges with four equivalent Mg(1)O3F3 octahedra. The Fe(2)-O(2) bond length is 2.27 Å. Both Fe(2)-O(1) bond lengths are 2.06 Å. The Fe(2)-F(1) bond length is 2.21 Å. Both Fe(2)-F(2) bond lengths are 2.15 Å. There are two inequivalent O sites. In the first O site, O(1) is bonded to one Mg(1), one Fe(1), and two equivalent Fe(2) atoms to form OMgFe3 tetrahedra that share corners with two equivalent O(2)Mg2Fe3 square pyramids, corners with two equivalent O(1)MgFe3 tetrahedra, and edges with two equivalent O(2)Mg2Fe3 square pyramids. In the second O site, O(2) is bonded to two equivalent Mg(1), one Fe(2), and two equivalent Fe(1) atoms to form OMg2Fe3 square pyramids that share corners with two equivalent O(1)MgFe3 tetrahedra, edges with two equivalent O(2)Mg2Fe3 square pyramids, and edges with two equivalent O(1)MgFe3 tetrahedra. There are two inequivalent F sites. In the first F site, F(1) is bonded in a distorted trigonal non-coplanar geometry to two equivalent Mg(1) and one Fe(2) atom. In the second F site, F(2) is bonded in a distorted trigonal non-coplanar geometry to one Mg(1) and two equivalent Fe(2) atoms.