MgFe6(OF)6 crystallizes in the triclinic P1 space group. Mg(1) is bonded to one O(1), two equivalent O(4), one F(6), and two equivalent F(2) atoms to form distorted MgO3F3 octahedra that share  a cornercorner with one Fe(5)O3F tetrahedra, edges with two equivalent Mg(1)O3F3 octahedra, and edges with four equivalent Fe(3)O3F3 octahedra. There are six inequivalent Fe sites. In the first Fe site, Fe(1) is bonded in a 6-coordinate geometry to one O(3), two equivalent O(2), one F(3), and two equivalent F(4) atoms. In the second Fe site, Fe(2) is bonded to one O(5), one O(6), two equivalent F(1), and two equivalent F(5) atoms to form FeO2F4 octahedra that share corners with four equivalent Fe(4)O4F2 octahedra, corners with four equivalent Fe(5)O3F tetrahedra, and edges with two equivalent Fe(2)O2F4 octahedra. The corner-sharing octahedral tilt angles range from 45-52°. In the third Fe site, Fe(3) is bonded to one O(4), two equivalent O(1), one F(2), and two equivalent F(6) atoms to form FeO3F3 octahedra that share corners with two equivalent Fe(5)O3F tetrahedra, edges with two equivalent Fe(3)O3F3 octahedra, and edges with four equivalent Mg(1)O3F3 octahedra. In the fourth Fe site, Fe(4) is bonded to two equivalent O(3), two equivalent O(6), one F(1), and one F(4) atom to form FeO4F2 octahedra that share corners with four equivalent Fe(2)O2F4 octahedra and edges with two equivalent Fe(4)O4F2 octahedra. The corner-sharing octahedral tilt angles range from 45-52°. In the fifth Fe site, Fe(5) is bonded to one O(1), two equivalent O(5), and one F(5) atom to form FeO3F tetrahedra that share  a cornercorner with one Mg(1)O3F3 octahedra, corners with two equivalent Fe(3)O3F3 octahedra, corners with four equivalent Fe(2)O2F4 octahedra, and corners with two equivalent Fe(5)O3F tetrahedra. The corner-sharing octahedral tilt angles range from 49-59°. In the sixth Fe site, Fe(6) is bonded in a 6-coordinate geometry to one O(2), two equivalent O(4), one F(6), and two equivalent F(3) atoms. There are six 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(5), and two equivalent Fe(3) atoms. In the second O site, O(2) is bonded in a trigonal planar geometry to one Fe(6) and two equivalent Fe(1) atoms. In the third O site, O(3) is bonded in a distorted trigonal planar geometry to one Fe(1) and two equivalent Fe(4) atoms. In the fourth O site, O(4) is bonded to two equivalent Mg(1), one Fe(3), and two equivalent Fe(6) atoms to form distorted edge-sharing OMg2Fe3 trigonal bipyramids. In the fifth O site, O(5) is bonded in a trigonal planar geometry to one Fe(2) and two equivalent Fe(5) atoms. In the sixth O site, O(6) is bonded in a trigonal planar geometry to one Fe(2) and two equivalent Fe(4) atoms. There are six inequivalent F sites. In the first F site, F(1) is bonded in a distorted T-shaped geometry to one Fe(4) and two equivalent Fe(2) atoms. In the second F site, F(2) is bonded in a distorted trigonal non-coplanar geometry to two equivalent Mg(1) and one Fe(3) atom. In the third F site, F(3) is bonded in a distorted water-like geometry to one Fe(1) and two equivalent Fe(6) atoms. In the fourth F site, F(4) is bonded in a distorted trigonal planar geometry to one Fe(4) and two equivalent Fe(1) atoms. In the fifth F site, F(5) is bonded in a 3-coordinate geometry to one Fe(5) and two equivalent Fe(2) atoms. In the sixth F site, F(6) is bonded in a distorted rectangular see-saw-like geometry to one Mg(1), one Fe(6), and two equivalent Fe(3) atoms.
MgFe6(OF)6 crystallizes in the triclinic P1 space group. Mg(1) is bonded to one O(1), two equivalent O(4), one F(6), and two equivalent F(2) atoms to form distorted MgO3F3 octahedra that share  a cornercorner with one Fe(5)O3F tetrahedra, edges with two equivalent Mg(1)O3F3 octahedra, and edges with four equivalent Fe(3)O3F3 octahedra. The Mg(1)-O(1) bond length is 1.97 Å. There is one shorter (2.25 Å) and one longer (2.29 Å) Mg(1)-O(4) bond length. The Mg(1)-F(6) bond length is 2.04 Å. Both Mg(1)-F(2) bond lengths are 1.95 Å. There are six inequivalent Fe sites. In the first Fe site, Fe(1) is bonded in a 6-coordinate geometry to one O(3), two equivalent O(2), one F(3), and two equivalent F(4) atoms. The Fe(1)-O(3) bond length is 1.86 Å. There is one shorter (2.01 Å) and one longer (2.02 Å) Fe(1)-O(2) bond length. The Fe(1)-F(3) bond length is 2.58 Å. There is one shorter (2.06 Å) and one longer (2.07 Å) Fe(1)-F(4) bond length. In the second Fe site, Fe(2) is bonded to one O(5), one O(6), two equivalent F(1), and two equivalent F(5) atoms to form FeO2F4 octahedra that share corners with four equivalent Fe(4)O4F2 octahedra, corners with four equivalent Fe(5)O3F tetrahedra, and edges with two equivalent Fe(2)O2F4 octahedra. The corner-sharing octahedral tilt angles range from 45-52°. The Fe(2)-O(5) bond length is 2.10 Å. The Fe(2)-O(6) bond length is 1.98 Å. Both Fe(2)-F(1) bond lengths are 2.14 Å. Both Fe(2)-F(5) bond lengths are 2.29 Å. In the third Fe site, Fe(3) is bonded to one O(4), two equivalent O(1), one F(2), and two equivalent F(6) atoms to form FeO3F3 octahedra that share corners with two equivalent Fe(5)O3F tetrahedra, edges with two equivalent Fe(3)O3F3 octahedra, and edges with four equivalent Mg(1)O3F3 octahedra. The Fe(3)-O(4) bond length is 2.11 Å. There is one shorter (2.07 Å) and one longer (2.13 Å) Fe(3)-O(1) bond length. The Fe(3)-F(2) bond length is 2.15 Å. There is one shorter (2.14 Å) and one longer (2.20 Å) Fe(3)-F(6) bond length. In the fourth Fe site, Fe(4) is bonded to two equivalent O(3), two equivalent O(6), one F(1), and one F(4) atom to form FeO4F2 octahedra that share corners with four equivalent Fe(2)O2F4 octahedra and edges with two equivalent Fe(4)O4F2 octahedra. The corner-sharing octahedral tilt angles range from 45-52°. Both Fe(4)-O(3) bond lengths are 2.05 Å. Both Fe(4)-O(6) bond lengths are 1.97 Å. The Fe(4)-F(1) bond length is 2.05 Å. The Fe(4)-F(4) bond length is 2.42 Å. In the fifth Fe site, Fe(5) is bonded to one O(1), two equivalent O(5), and one F(5) atom to form FeO3F tetrahedra that share  a cornercorner with one Mg(1)O3F3 octahedra, corners with two equivalent Fe(3)O3F3 octahedra, corners with four equivalent Fe(2)O2F4 octahedra, and corners with two equivalent Fe(5)O3F tetrahedra. The corner-sharing octahedral tilt angles range from 49-59°. The Fe(5)-O(1) bond length is 1.91 Å. Both Fe(5)-O(5) bond lengths are 1.86 Å. The Fe(5)-F(5) bond length is 1.94 Å. In the sixth Fe site, Fe(6) is bonded in a 6-coordinate geometry to one O(2), two equivalent O(4), one F(6), and two equivalent F(3) atoms. The Fe(6)-O(2) bond length is 1.87 Å. Both Fe(6)-O(4) bond lengths are 2.07 Å. The Fe(6)-F(6) bond length is 2.44 Å. There is one shorter (2.03 Å) and one longer (2.04 Å) Fe(6)-F(3) bond length. There are six 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(5), and two equivalent Fe(3) atoms. In the second O site, O(2) is bonded in a trigonal planar geometry to one Fe(6) and two equivalent Fe(1) atoms. In the third O site, O(3) is bonded in a distorted trigonal planar geometry to one Fe(1) and two equivalent Fe(4) atoms. In the fourth O site, O(4) is bonded to two equivalent Mg(1), one Fe(3), and two equivalent Fe(6) atoms to form distorted edge-sharing OMg2Fe3 trigonal bipyramids. In the fifth O site, O(5) is bonded in a trigonal planar geometry to one Fe(2) and two equivalent Fe(5) atoms. In the sixth O site, O(6) is bonded in a trigonal planar geometry to one Fe(2) and two equivalent Fe(4) atoms. There are six inequivalent F sites. In the first F site, F(1) is bonded in a distorted T-shaped geometry to one Fe(4) and two equivalent Fe(2) atoms. In the second F site, F(2) is bonded in a distorted trigonal non-coplanar geometry to two equivalent Mg(1) and one Fe(3) atom. In the third F site, F(3) is bonded in a distorted water-like geometry to one Fe(1) and two equivalent Fe(6) atoms. In the fourth F site, F(4) is bonded in a distorted trigonal planar geometry to one Fe(4) and two equivalent Fe(1) atoms. In the fifth F site, F(5) is bonded in a 3-coordinate geometry to one Fe(5) and two equivalent Fe(2) atoms. In the sixth F site, F(6) is bonded in a distorted rectangular see-saw-like geometry to one Mg(1), one Fe(6), and two equivalent Fe(3) atoms.