MgFe4O5F3 crystallizes in the triclinic P1 space group. Mg(1) is bonded to one O(1), one O(2), one O(4), one F(2), and one F(3) atom to form distorted MgO3F2 trigonal bipyramids that share corners with three equivalent Fe(2)O3F3 octahedra,  a cornercorner with one Fe(3)O5 trigonal bipyramid,  an edgeedge with one Fe(1)O3F3 octahedra,  an edgeedge with one Fe(3)O5 trigonal bipyramid, and  a faceface with one Fe(1)O3F3 octahedra. The corner-sharing octahedral tilt angles range from 38-59°. 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(2), and one F(3) atom to form FeO3F3 octahedra that share corners with three equivalent Fe(3)O5 trigonal bipyramids, edges with two equivalent Fe(2)O3F3 octahedra,  an edgeedge with one Mg(1)O3F2 trigonal bipyramid, and  a faceface with one Mg(1)O3F2 trigonal bipyramid. In the second Fe site, Fe(2) is bonded to one O(1), one O(3), one O(5), one F(1), one F(2), and one F(3) atom to form FeO3F3 octahedra that share corners with three equivalent Mg(1)O3F2 trigonal bipyramids, corners with three equivalent Fe(3)O5 trigonal bipyramids, and edges with two equivalent Fe(1)O3F3 octahedra. In the third Fe site, Fe(3) is bonded to one O(1), one O(2), one O(3), one O(4), and one O(5) atom to form distorted FeO5 trigonal bipyramids that share corners with three equivalent Fe(1)O3F3 octahedra, corners with three equivalent Fe(2)O3F3 octahedra,  a cornercorner with one Mg(1)O3F2 trigonal bipyramid, and  an edgeedge with one Mg(1)O3F2 trigonal bipyramid. The corner-sharing octahedral tilt angles range from 36-57°. In the fourth Fe site, Fe(4) is bonded in a square co-planar geometry to one O(2), one O(3), one O(4), and one O(5) atom. There are five inequivalent O sites. In the first O site, O(1) is bonded in a see-saw-like geometry to one Mg(1), one Fe(1), one Fe(2), and one Fe(3) atom. In the second O site, O(2) is bonded to one Mg(1), one Fe(1), one Fe(3), and one Fe(4) atom to form a mixture of distorted edge and corner-sharing OMgFe3 tetrahedra. In the third O site, O(3) is bonded in a distorted trigonal planar geometry to one Fe(2), one Fe(3), and one Fe(4) atom. In the fourth O site, O(4) is bonded to one Mg(1), one Fe(1), one Fe(3), and one Fe(4) atom to form a mixture of edge and corner-sharing OMgFe3 trigonal pyramids. In the fifth O site, O(5) is bonded in a distorted trigonal planar geometry to one Fe(2), one Fe(3), and one Fe(4) atom. There are three inequivalent F sites. In the first F site, F(1) is bonded in a water-like geometry to one Fe(1) and one Fe(2) atom. In the second F site, F(2) is bonded in a distorted T-shaped geometry to one Mg(1), one Fe(1), and one Fe(2) atom. In the third F site, F(3) is bonded in a T-shaped geometry to one Mg(1), one Fe(1), and one Fe(2) atom.
MgFe4O5F3 crystallizes in the triclinic P1 space group. Mg(1) is bonded to one O(1), one O(2), one O(4), one F(2), and one F(3) atom to form distorted MgO3F2 trigonal bipyramids that share corners with three equivalent Fe(2)O3F3 octahedra,  a cornercorner with one Fe(3)O5 trigonal bipyramid,  an edgeedge with one Fe(1)O3F3 octahedra,  an edgeedge with one Fe(3)O5 trigonal bipyramid, and  a faceface with one Fe(1)O3F3 octahedra. The corner-sharing octahedral tilt angles range from 38-59°. The Mg(1)-O(1) bond length is 2.14 Å. The Mg(1)-O(2) bond length is 1.95 Å. The Mg(1)-O(4) bond length is 2.01 Å. The Mg(1)-F(2) bond length is 1.96 Å. The Mg(1)-F(3) bond length is 2.08 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(2), and one F(3) atom to form FeO3F3 octahedra that share corners with three equivalent Fe(3)O5 trigonal bipyramids, edges with two equivalent Fe(2)O3F3 octahedra,  an edgeedge with one Mg(1)O3F2 trigonal bipyramid, and  a faceface with one Mg(1)O3F2 trigonal bipyramid. The Fe(1)-O(1) bond length is 1.98 Å. The Fe(1)-O(2) bond length is 2.01 Å. The Fe(1)-O(4) bond length is 1.95 Å. The Fe(1)-F(1) bond length is 1.96 Å. The Fe(1)-F(2) bond length is 2.11 Å. The Fe(1)-F(3) bond length is 2.13 Å. In the second Fe site, Fe(2) is bonded to one O(1), one O(3), one O(5), one F(1), one F(2), and one F(3) atom to form FeO3F3 octahedra that share corners with three equivalent Mg(1)O3F2 trigonal bipyramids, corners with three equivalent Fe(3)O5 trigonal bipyramids, and edges with two equivalent Fe(1)O3F3 octahedra. The Fe(2)-O(1) bond length is 2.11 Å. The Fe(2)-O(3) bond length is 1.92 Å. The Fe(2)-O(5) bond length is 1.91 Å. The Fe(2)-F(1) bond length is 2.04 Å. The Fe(2)-F(2) bond length is 2.16 Å. The Fe(2)-F(3) bond length is 2.24 Å. In the third Fe site, Fe(3) is bonded to one O(1), one O(2), one O(3), one O(4), and one O(5) atom to form distorted FeO5 trigonal bipyramids that share corners with three equivalent Fe(1)O3F3 octahedra, corners with three equivalent Fe(2)O3F3 octahedra,  a cornercorner with one Mg(1)O3F2 trigonal bipyramid, and  an edgeedge with one Mg(1)O3F2 trigonal bipyramid. The corner-sharing octahedral tilt angles range from 36-57°. The Fe(3)-O(1) bond length is 2.05 Å. The Fe(3)-O(2) bond length is 2.07 Å. The Fe(3)-O(3) bond length is 1.94 Å. The Fe(3)-O(4) bond length is 2.06 Å. The Fe(3)-O(5) bond length is 1.99 Å. In the fourth Fe site, Fe(4) is bonded in a square co-planar geometry to one O(2), one O(3), one O(4), and one O(5) atom. The Fe(4)-O(2) bond length is 2.08 Å. The Fe(4)-O(3) bond length is 2.03 Å. The Fe(4)-O(4) bond length is 2.08 Å. The Fe(4)-O(5) bond length is 2.04 Å. There are five inequivalent O sites. In the first O site, O(1) is bonded in a see-saw-like geometry to one Mg(1), one Fe(1), one Fe(2), and one Fe(3) atom. In the second O site, O(2) is bonded to one Mg(1), one Fe(1), one Fe(3), and one Fe(4) atom to form a mixture of distorted edge and corner-sharing OMgFe3 tetrahedra. In the third O site, O(3) is bonded in a distorted trigonal planar geometry to one Fe(2), one Fe(3), and one Fe(4) atom. In the fourth O site, O(4) is bonded to one Mg(1), one Fe(1), one Fe(3), and one Fe(4) atom to form a mixture of edge and corner-sharing OMgFe3 trigonal pyramids. In the fifth O site, O(5) is bonded in a distorted trigonal planar geometry to one Fe(2), one Fe(3), and one Fe(4) atom. There are three inequivalent F sites. In the first F site, F(1) is bonded in a water-like geometry to one Fe(1) and one Fe(2) atom. In the second F site, F(2) is bonded in a distorted T-shaped geometry to one Mg(1), one Fe(1), and one Fe(2) atom. In the third F site, F(3) is bonded in a T-shaped geometry to one Mg(1), one Fe(1), and one Fe(2) atom.