MgFe6O7F5 crystallizes in the monoclinic Pm space group. Mg(1) is bonded to one O(3), two equivalent O(1), one F(2), and two equivalent F(4) atoms to form distorted MgO3F3 octahedra that share corners with four equivalent Fe(1)O3F3 octahedra, corners with two equivalent Fe(4)O4F trigonal bipyramids, edges with two equivalent Fe(4)O4F trigonal bipyramids, and faces with two equivalent Fe(2)O3F3 octahedra. The corner-sharing octahedral tilt angles range from 42-48°. There are four inequivalent Fe sites. In the first Fe site, Fe(1) is bonded to one O(1), one O(2), one O(4), one F(1), one F(3), and one F(4) atom to form FeO3F3 octahedra that share corners with two equivalent Mg(1)O3F3 octahedra, corners with three equivalent Fe(3)O4F square pyramids, corners with three equivalent Fe(4)O4F trigonal bipyramids,  an edgeedge with one Fe(1)O3F3 octahedra, and  an edgeedge with one Fe(2)O3F3 octahedra. The corner-sharing octahedral tilt angles range from 42-48°. In the second Fe site, Fe(2) is bonded to one O(3), two equivalent O(1), one F(2), and two equivalent F(4) atoms to form FeO3F3 octahedra that share corners with six equivalent Fe(4)O4F trigonal bipyramids, edges with two equivalent Fe(1)O3F3 octahedra, and faces with two equivalent Mg(1)O3F3 octahedra. In the third Fe site, Fe(3) is bonded to two equivalent O(2), two equivalent O(4), and one F(3) atom to form distorted FeO4F square pyramids that share corners with six equivalent Fe(1)O3F3 octahedra and edges with two equivalent Fe(4)O4F trigonal bipyramids. The corner-sharing octahedral tilt angles range from 44-49°. In the fourth Fe site, Fe(4) is bonded to one O(1), one O(2), one O(3), one O(4), and one F(2) atom to form distorted FeO4F trigonal bipyramids that share  a cornercorner with one Mg(1)O3F3 octahedra, corners with three equivalent Fe(1)O3F3 octahedra, corners with three equivalent Fe(2)O3F3 octahedra,  an edgeedge with one Mg(1)O3F3 octahedra,  an edgeedge with one Fe(3)O4F square pyramid, and  an edgeedge with one Fe(4)O4F trigonal bipyramid. The corner-sharing octahedral tilt angles range from 40-70°. There are four inequivalent O sites. In the first O site, O(1) is bonded in a rectangular see-saw-like geometry to one Mg(1), one Fe(1), one Fe(2), and one Fe(4) atom. In the second O site, O(2) is bonded in a distorted trigonal planar geometry to one Fe(1), one Fe(3), and one Fe(4) atom. In the third O site, O(3) is bonded to one Mg(1), one Fe(2), and two equivalent Fe(4) atoms to form OMgFe3 tetrahedra that share corners with two equivalent F(2)MgFe3 trigonal pyramids and  an edgeedge with one F(2)MgFe3 trigonal pyramid. In the fourth O site, O(4) is bonded in a distorted trigonal planar geometry to one Fe(1), one Fe(3), and one Fe(4) atom. There are four inequivalent F sites. In the first F site, F(1) is bonded in a water-like geometry to two equivalent Fe(1) atoms. In the second F site, F(2) is bonded to one Mg(1), one Fe(2), and two equivalent Fe(4) atoms to form FMgFe3 trigonal pyramids that share corners with two equivalent O(3)MgFe3 tetrahedra and  an edgeedge with one O(3)MgFe3 tetrahedra. In the third F site, F(3) is bonded in a 3-coordinate geometry to one Fe(3) and two equivalent Fe(1) atoms. In the fourth F site, F(4) is bonded in a T-shaped geometry to one Mg(1), one Fe(1), and one Fe(2) atom.
MgFe6O7F5 crystallizes in the monoclinic Pm space group. Mg(1) is bonded to one O(3), two equivalent O(1), one F(2), and two equivalent F(4) atoms to form distorted MgO3F3 octahedra that share corners with four equivalent Fe(1)O3F3 octahedra, corners with two equivalent Fe(4)O4F trigonal bipyramids, edges with two equivalent Fe(4)O4F trigonal bipyramids, and faces with two equivalent Fe(2)O3F3 octahedra. The corner-sharing octahedral tilt angles range from 42-48°. The Mg(1)-O(3) bond length is 1.97 Å. Both Mg(1)-O(1) bond lengths are 2.22 Å. The Mg(1)-F(2) bond length is 1.99 Å. Both Mg(1)-F(4) bond lengths are 2.03 Å. There are four inequivalent Fe sites. In the first Fe site, Fe(1) is bonded to one O(1), one O(2), one O(4), one F(1), one F(3), and one F(4) atom to form FeO3F3 octahedra that share corners with two equivalent Mg(1)O3F3 octahedra, corners with three equivalent Fe(3)O4F square pyramids, corners with three equivalent Fe(4)O4F trigonal bipyramids,  an edgeedge with one Fe(1)O3F3 octahedra, and  an edgeedge with one Fe(2)O3F3 octahedra. The corner-sharing octahedral tilt angles range from 42-48°. The Fe(1)-O(1) bond length is 2.00 Å. The Fe(1)-O(2) bond length is 1.98 Å. The Fe(1)-O(4) bond length is 1.97 Å. The Fe(1)-F(1) bond length is 1.98 Å. The Fe(1)-F(3) bond length is 2.27 Å. The Fe(1)-F(4) bond length is 2.12 Å. In the second Fe site, Fe(2) is bonded to one O(3), two equivalent O(1), one F(2), and two equivalent F(4) atoms to form FeO3F3 octahedra that share corners with six equivalent Fe(4)O4F trigonal bipyramids, edges with two equivalent Fe(1)O3F3 octahedra, and faces with two equivalent Mg(1)O3F3 octahedra. The Fe(2)-O(3) bond length is 2.05 Å. Both Fe(2)-O(1) bond lengths are 2.06 Å. The Fe(2)-F(2) bond length is 2.07 Å. Both Fe(2)-F(4) bond lengths are 2.12 Å. In the third Fe site, Fe(3) is bonded to two equivalent O(2), two equivalent O(4), and one F(3) atom to form distorted FeO4F square pyramids that share corners with six equivalent Fe(1)O3F3 octahedra and edges with two equivalent Fe(4)O4F trigonal bipyramids. The corner-sharing octahedral tilt angles range from 44-49°. Both Fe(3)-O(2) bond lengths are 2.02 Å. Both Fe(3)-O(4) bond lengths are 2.01 Å. The Fe(3)-F(3) bond length is 2.02 Å. In the fourth Fe site, Fe(4) is bonded to one O(1), one O(2), one O(3), one O(4), and one F(2) atom to form distorted FeO4F trigonal bipyramids that share  a cornercorner with one Mg(1)O3F3 octahedra, corners with three equivalent Fe(1)O3F3 octahedra, corners with three equivalent Fe(2)O3F3 octahedra,  an edgeedge with one Mg(1)O3F3 octahedra,  an edgeedge with one Fe(3)O4F square pyramid, and  an edgeedge with one Fe(4)O4F trigonal bipyramid. The corner-sharing octahedral tilt angles range from 40-70°. The Fe(4)-O(1) bond length is 1.93 Å. The Fe(4)-O(2) bond length is 1.89 Å. The Fe(4)-O(3) bond length is 2.02 Å. The Fe(4)-O(4) bond length is 1.96 Å. The Fe(4)-F(2) bond length is 2.28 Å. There are four inequivalent O sites. In the first O site, O(1) is bonded in a rectangular see-saw-like geometry to one Mg(1), one Fe(1), one Fe(2), and one Fe(4) atom. In the second O site, O(2) is bonded in a distorted trigonal planar geometry to one Fe(1), one Fe(3), and one Fe(4) atom. In the third O site, O(3) is bonded to one Mg(1), one Fe(2), and two equivalent Fe(4) atoms to form OMgFe3 tetrahedra that share corners with two equivalent F(2)MgFe3 trigonal pyramids and  an edgeedge with one F(2)MgFe3 trigonal pyramid. In the fourth O site, O(4) is bonded in a distorted trigonal planar geometry to one Fe(1), one Fe(3), and one Fe(4) atom. There are four inequivalent F sites. In the first F site, F(1) is bonded in a water-like geometry to two equivalent Fe(1) atoms. In the second F site, F(2) is bonded to one Mg(1), one Fe(2), and two equivalent Fe(4) atoms to form FMgFe3 trigonal pyramids that share corners with two equivalent O(3)MgFe3 tetrahedra and  an edgeedge with one O(3)MgFe3 tetrahedra. In the third F site, F(3) is bonded in a 3-coordinate geometry to one Fe(3) and two equivalent Fe(1) atoms. In the fourth F site, F(4) is bonded in a T-shaped geometry to one Mg(1), one Fe(1), and one Fe(2) atom.