MgFe4(OF)4 crystallizes in the triclinic P1 space group. Mg(1) is bonded to one O(1), one O(2), one O(3), one O(4), and one F(3) atom to form MgO4F trigonal bipyramids that share  a cornercorner with one Fe(1)O2F4 octahedra, corners with three equivalent Fe(2)O3F2 trigonal bipyramids,  an edgeedge with one Fe(1)O2F4 octahedra, edges with two equivalent Fe(3)O3F3 octahedra, and edges with two equivalent Fe(4)O4F2 octahedra. The corner-sharing octahedral tilt angles are 70°. There are four inequivalent Fe sites. In the first Fe site, Fe(1) is bonded to one O(2), one O(3), one F(1), one F(2), one F(3), and one F(4) atom to form FeO2F4 octahedra that share corners with two equivalent Fe(3)O3F3 octahedra,  a cornercorner with one Mg(1)O4F trigonal bipyramid, corners with three equivalent Fe(2)O3F2 trigonal bipyramids,  an edgeedge with one Fe(3)O3F3 octahedra, edges with two equivalent Fe(4)O4F2 octahedra, and  an edgeedge with one Mg(1)O4F trigonal bipyramid. The corner-sharing octahedral tilt angles range from 15-16°. In the second Fe site, Fe(2) is bonded to one O(1), one O(2), one O(4), one F(1), and one F(2) atom to form FeO3F2 trigonal bipyramids that share  a cornercorner with one Fe(3)O3F3 octahedra, corners with three equivalent Fe(1)O2F4 octahedra, corners with three equivalent Mg(1)O4F trigonal bipyramids,  an edgeedge with one Fe(3)O3F3 octahedra, and edges with two equivalent Fe(4)O4F2 octahedra. The corner-sharing octahedral tilt angles range from 17-69°. In the third Fe site, Fe(3) is bonded to one O(1), one O(3), one O(4), one F(1), one F(3), and one F(4) atom to form FeO3F3 octahedra that share corners with two equivalent Fe(1)O2F4 octahedra, corners with two equivalent Fe(4)O4F2 octahedra,  a cornercorner with one Fe(2)O3F2 trigonal bipyramid,  an edgeedge with one Fe(1)O2F4 octahedra,  an edgeedge with one Fe(4)O4F2 octahedra,  an edgeedge with one Fe(2)O3F2 trigonal bipyramid, and edges with two equivalent Mg(1)O4F trigonal bipyramids. The corner-sharing octahedral tilt angles range from 15-32°. In the fourth Fe site, Fe(4) is bonded to one O(1), one O(2), one O(3), one O(4), one F(2), and one F(4) atom to form distorted FeO4F2 octahedra that share corners with two equivalent Fe(3)O3F3 octahedra,  an edgeedge with one Fe(3)O3F3 octahedra, edges with two equivalent Fe(1)O2F4 octahedra, edges with two equivalent Mg(1)O4F trigonal bipyramids, and edges with two equivalent Fe(2)O3F2 trigonal bipyramids. The corner-sharing octahedral tilt angles range from 25-32°. There are four inequivalent O sites. In the first O site, O(1) is bonded in a see-saw-like geometry to one Mg(1), one Fe(2), one Fe(3), and one Fe(4) atom. In the second O site, O(2) is bonded to one Mg(1), one Fe(1), one Fe(2), and one Fe(4) atom to form a mixture of corner and edge-sharing OMgFe3 trigonal pyramids. In the third O site, O(3) is bonded to one Mg(1), one Fe(1), one Fe(3), and one Fe(4) atom to form a mixture of corner and edge-sharing OMgFe3 trigonal pyramids. In the fourth O site, O(4) is bonded in a see-saw-like geometry to one Mg(1), one Fe(2), 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 distorted T-shaped geometry to one Fe(1), one Fe(2), and one Fe(3) atom. In the second F site, F(2) is bonded in a T-shaped geometry to one Fe(1), one Fe(2), and one Fe(4) 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(3) atom. In the fourth F site, F(4) is bonded in a T-shaped geometry to one Fe(1), one Fe(3), and one Fe(4) atom.
MgFe4(OF)4 crystallizes in the triclinic P1 space group. Mg(1) is bonded to one O(1), one O(2), one O(3), one O(4), and one F(3) atom to form MgO4F trigonal bipyramids that share  a cornercorner with one Fe(1)O2F4 octahedra, corners with three equivalent Fe(2)O3F2 trigonal bipyramids,  an edgeedge with one Fe(1)O2F4 octahedra, edges with two equivalent Fe(3)O3F3 octahedra, and edges with two equivalent Fe(4)O4F2 octahedra. The corner-sharing octahedral tilt angles are 70°. The Mg(1)-O(1) bond length is 2.03 Å. The Mg(1)-O(2) bond length is 2.03 Å. The Mg(1)-O(3) bond length is 2.11 Å. The Mg(1)-O(4) bond length is 2.09 Å. The Mg(1)-F(3) bond length is 1.99 Å. There are four inequivalent Fe sites. In the first Fe site, Fe(1) is bonded to one O(2), one O(3), one F(1), one F(2), one F(3), and one F(4) atom to form FeO2F4 octahedra that share corners with two equivalent Fe(3)O3F3 octahedra,  a cornercorner with one Mg(1)O4F trigonal bipyramid, corners with three equivalent Fe(2)O3F2 trigonal bipyramids,  an edgeedge with one Fe(3)O3F3 octahedra, edges with two equivalent Fe(4)O4F2 octahedra, and  an edgeedge with one Mg(1)O4F trigonal bipyramid. The corner-sharing octahedral tilt angles range from 15-16°. The Fe(1)-O(2) bond length is 2.12 Å. The Fe(1)-O(3) bond length is 2.10 Å. The Fe(1)-F(1) bond length is 2.27 Å. The Fe(1)-F(2) bond length is 2.15 Å. The Fe(1)-F(3) bond length is 2.11 Å. The Fe(1)-F(4) bond length is 2.11 Å. In the second Fe site, Fe(2) is bonded to one O(1), one O(2), one O(4), one F(1), and one F(2) atom to form FeO3F2 trigonal bipyramids that share  a cornercorner with one Fe(3)O3F3 octahedra, corners with three equivalent Fe(1)O2F4 octahedra, corners with three equivalent Mg(1)O4F trigonal bipyramids,  an edgeedge with one Fe(3)O3F3 octahedra, and edges with two equivalent Fe(4)O4F2 octahedra. The corner-sharing octahedral tilt angles range from 17-69°. The Fe(2)-O(1) bond length is 1.95 Å. The Fe(2)-O(2) bond length is 1.96 Å. The Fe(2)-O(4) bond length is 1.94 Å. The Fe(2)-F(1) bond length is 1.97 Å. The Fe(2)-F(2) bond length is 2.12 Å. In the third Fe site, Fe(3) is bonded to one O(1), one O(3), one O(4), one F(1), one F(3), and one F(4) atom to form FeO3F3 octahedra that share corners with two equivalent Fe(1)O2F4 octahedra, corners with two equivalent Fe(4)O4F2 octahedra,  a cornercorner with one Fe(2)O3F2 trigonal bipyramid,  an edgeedge with one Fe(1)O2F4 octahedra,  an edgeedge with one Fe(4)O4F2 octahedra,  an edgeedge with one Fe(2)O3F2 trigonal bipyramid, and edges with two equivalent Mg(1)O4F trigonal bipyramids. The corner-sharing octahedral tilt angles range from 15-32°. The Fe(3)-O(1) bond length is 2.18 Å. The Fe(3)-O(3) bond length is 2.01 Å. The Fe(3)-O(4) bond length is 2.19 Å. The Fe(3)-F(1) bond length is 2.22 Å. The Fe(3)-F(3) bond length is 2.16 Å. The Fe(3)-F(4) bond length is 2.06 Å. In the fourth Fe site, Fe(4) is bonded to one O(1), one O(2), one O(3), one O(4), one F(2), and one F(4) atom to form distorted FeO4F2 octahedra that share corners with two equivalent Fe(3)O3F3 octahedra,  an edgeedge with one Fe(3)O3F3 octahedra, edges with two equivalent Fe(1)O2F4 octahedra, edges with two equivalent Mg(1)O4F trigonal bipyramids, and edges with two equivalent Fe(2)O3F2 trigonal bipyramids. The corner-sharing octahedral tilt angles range from 25-32°. The Fe(4)-O(1) bond length is 2.01 Å. The Fe(4)-O(2) bond length is 2.07 Å. The Fe(4)-O(3) bond length is 1.91 Å. The Fe(4)-O(4) bond length is 1.97 Å. The Fe(4)-F(2) bond length is 2.16 Å. The Fe(4)-F(4) bond length is 2.31 Å. There are four inequivalent O sites. In the first O site, O(1) is bonded in a see-saw-like geometry to one Mg(1), one Fe(2), one Fe(3), and one Fe(4) atom. In the second O site, O(2) is bonded to one Mg(1), one Fe(1), one Fe(2), and one Fe(4) atom to form a mixture of corner and edge-sharing OMgFe3 trigonal pyramids. In the third O site, O(3) is bonded to one Mg(1), one Fe(1), one Fe(3), and one Fe(4) atom to form a mixture of corner and edge-sharing OMgFe3 trigonal pyramids. In the fourth O site, O(4) is bonded in a see-saw-like geometry to one Mg(1), one Fe(2), 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 distorted T-shaped geometry to one Fe(1), one Fe(2), and one Fe(3) atom. In the second F site, F(2) is bonded in a T-shaped geometry to one Fe(1), one Fe(2), and one Fe(4) 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(3) atom. In the fourth F site, F(4) is bonded in a T-shaped geometry to one Fe(1), one Fe(3), and one Fe(4) atom.