MgFe6(OF)6 crystallizes in the monoclinic Pm space group. Mg(1) is bonded to two equivalent O(5), one F(1), one F(6), and two equivalent F(3) atoms to form MgO2F4 octahedra that share corners with two equivalent Fe(6)O3F2 trigonal bipyramids, edges with two equivalent Mg(1)O2F4 octahedra, edges with two equivalent Fe(1)O3F3 octahedra, edges with two equivalent Fe(3)O3F3 octahedra, and  an edgeedge with one Fe(6)O3F2 trigonal bipyramid. There are six inequivalent Fe sites. In the first Fe site, Fe(1) is bonded to one O(3), two equivalent O(6), one F(3), and two equivalent F(1) atoms to form distorted FeO3F3 octahedra that share corners with two equivalent Fe(4)O3F2 square pyramids, corners with two equivalent Fe(6)O3F2 trigonal bipyramids, edges with two equivalent Mg(1)O2F4 octahedra, and edges with two equivalent Fe(1)O3F3 octahedra. In the second Fe site, Fe(2) is bonded to one O(4), two equivalent O(1), one F(4), and two equivalent F(5) atoms to form FeO3F3 octahedra that share corners with two equivalent Fe(4)O3F2 square pyramids, corners with two equivalent Fe(6)O3F2 trigonal bipyramids, and edges with two equivalent Fe(2)O3F3 octahedra. In the third Fe site, Fe(3) is bonded to one O(5), two equivalent O(2), one F(2), and two equivalent F(6) atoms to form FeO3F3 octahedra that share corners with two equivalent Fe(4)O3F2 square pyramids, corners with two equivalent Fe(6)O3F2 trigonal bipyramids, edges with two equivalent Mg(1)O2F4 octahedra, and edges with two equivalent Fe(3)O3F3 octahedra. In the fourth Fe site, Fe(4) is bonded to one O(1), two equivalent O(3), and two equivalent F(2) atoms to form distorted FeO3F2 square pyramids that share corners with two equivalent Fe(1)O3F3 octahedra, corners with two equivalent Fe(2)O3F3 octahedra, corners with two equivalent Fe(3)O3F3 octahedra, and edges with two equivalent Fe(4)O3F2 square pyramids. The corner-sharing octahedral tilt angles range from 47-56°. In the fifth Fe site, Fe(5) is bonded in a trigonal planar geometry to one O(2) and two equivalent O(4) atoms. In the sixth Fe site, Fe(6) is bonded to one O(6), two equivalent O(5), and two equivalent F(4) atoms to form distorted FeO3F2 trigonal bipyramids that share corners with two equivalent Mg(1)O2F4 octahedra, corners with two equivalent Fe(1)O3F3 octahedra, corners with two equivalent Fe(2)O3F3 octahedra, corners with two equivalent Fe(3)O3F3 octahedra,  an edgeedge with one Mg(1)O2F4 octahedra, and edges with two equivalent Fe(6)O3F2 trigonal bipyramids. The corner-sharing octahedral tilt angles range from 30-67°. There are six inequivalent O sites. In the first O site, O(1) is bonded in a distorted trigonal planar geometry to one Fe(4) and two equivalent Fe(2) atoms. In the second O site, O(2) is bonded in a trigonal planar geometry to one Fe(5) and two equivalent Fe(3) atoms. In the third O site, O(3) is bonded in a trigonal planar geometry to one Fe(1) and two equivalent Fe(4) atoms. In the fourth O site, O(4) is bonded in a trigonal planar geometry to one Fe(2) and two equivalent Fe(5) atoms. In the fifth O site, O(5) 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 sixth O site, O(6) is bonded in a trigonal planar geometry to one Fe(6) and two equivalent Fe(1) atoms. There are six inequivalent F sites. In the first F site, F(1) is bonded in a trigonal non-coplanar geometry to one Mg(1) and two equivalent Fe(1) atoms. In the second F site, F(2) is bonded in a distorted T-shaped geometry to one Fe(3) and two equivalent Fe(4) atoms. In the third F site, F(3) is bonded in a distorted trigonal non-coplanar geometry to two equivalent Mg(1) and one Fe(1) atom. In the fourth F site, F(4) is bonded in a distorted T-shaped geometry to one Fe(2) and two equivalent Fe(6) atoms. In the fifth F site, F(5) is bonded in a water-like geometry to two equivalent Fe(2) atoms. In the sixth F site, F(6) is bonded in a distorted T-shaped geometry to one Mg(1) and two equivalent Fe(3) atoms.
MgFe6(OF)6 crystallizes in the monoclinic Pm space group. Mg(1) is bonded to two equivalent O(5), one F(1), one F(6), and two equivalent F(3) atoms to form MgO2F4 octahedra that share corners with two equivalent Fe(6)O3F2 trigonal bipyramids, edges with two equivalent Mg(1)O2F4 octahedra, edges with two equivalent Fe(1)O3F3 octahedra, edges with two equivalent Fe(3)O3F3 octahedra, and  an edgeedge with one Fe(6)O3F2 trigonal bipyramid. Both Mg(1)-O(5) bond lengths are 2.15 Å. The Mg(1)-F(1) bond length is 2.00 Å. The Mg(1)-F(6) bond length is 1.98 Å. Both Mg(1)-F(3) bond lengths are 2.02 Å. There are six inequivalent Fe sites. In the first Fe site, Fe(1) is bonded to one O(3), two equivalent O(6), one F(3), and two equivalent F(1) atoms to form distorted FeO3F3 octahedra that share corners with two equivalent Fe(4)O3F2 square pyramids, corners with two equivalent Fe(6)O3F2 trigonal bipyramids, edges with two equivalent Mg(1)O2F4 octahedra, and edges with two equivalent Fe(1)O3F3 octahedra. The Fe(1)-O(3) bond length is 1.94 Å. Both Fe(1)-O(6) bond lengths are 1.93 Å. The Fe(1)-F(3) bond length is 2.24 Å. Both Fe(1)-F(1) bond lengths are 2.15 Å. In the second Fe site, Fe(2) is bonded to one O(4), two equivalent O(1), one F(4), and two equivalent F(5) atoms to form FeO3F3 octahedra that share corners with two equivalent Fe(4)O3F2 square pyramids, corners with two equivalent Fe(6)O3F2 trigonal bipyramids, and edges with two equivalent Fe(2)O3F3 octahedra. The Fe(2)-O(4) bond length is 1.93 Å. Both Fe(2)-O(1) bond lengths are 2.00 Å. The Fe(2)-F(4) bond length is 2.10 Å. Both Fe(2)-F(5) bond lengths are 2.05 Å. In the third Fe site, Fe(3) is bonded to one O(5), two equivalent O(2), one F(2), and two equivalent F(6) atoms to form FeO3F3 octahedra that share corners with two equivalent Fe(4)O3F2 square pyramids, corners with two equivalent Fe(6)O3F2 trigonal bipyramids, edges with two equivalent Mg(1)O2F4 octahedra, and edges with two equivalent Fe(3)O3F3 octahedra. The Fe(3)-O(5) bond length is 1.99 Å. Both Fe(3)-O(2) bond lengths are 1.93 Å. The Fe(3)-F(2) bond length is 2.16 Å. Both Fe(3)-F(6) bond lengths are 2.14 Å. In the fourth Fe site, Fe(4) is bonded to one O(1), two equivalent O(3), and two equivalent F(2) atoms to form distorted FeO3F2 square pyramids that share corners with two equivalent Fe(1)O3F3 octahedra, corners with two equivalent Fe(2)O3F3 octahedra, corners with two equivalent Fe(3)O3F3 octahedra, and edges with two equivalent Fe(4)O3F2 square pyramids. The corner-sharing octahedral tilt angles range from 47-56°. The Fe(4)-O(1) bond length is 1.86 Å. Both Fe(4)-O(3) bond lengths are 1.94 Å. Both Fe(4)-F(2) bond lengths are 2.16 Å. In the fifth Fe site, Fe(5) is bonded in a trigonal planar geometry to one O(2) and two equivalent O(4) atoms. The Fe(5)-O(2) bond length is 1.97 Å. Both Fe(5)-O(4) bond lengths are 1.91 Å. In the sixth Fe site, Fe(6) is bonded to one O(6), two equivalent O(5), and two equivalent F(4) atoms to form distorted FeO3F2 trigonal bipyramids that share corners with two equivalent Mg(1)O2F4 octahedra, corners with two equivalent Fe(1)O3F3 octahedra, corners with two equivalent Fe(2)O3F3 octahedra, corners with two equivalent Fe(3)O3F3 octahedra,  an edgeedge with one Mg(1)O2F4 octahedra, and edges with two equivalent Fe(6)O3F2 trigonal bipyramids. The corner-sharing octahedral tilt angles range from 30-67°. The Fe(6)-O(6) bond length is 1.99 Å. Both Fe(6)-O(5) bond lengths are 2.23 Å. Both Fe(6)-F(4) bond lengths are 2.11 Å. There are six inequivalent O sites. In the first O site, O(1) is bonded in a distorted trigonal planar geometry to one Fe(4) and two equivalent Fe(2) atoms. In the second O site, O(2) is bonded in a trigonal planar geometry to one Fe(5) and two equivalent Fe(3) atoms. In the third O site, O(3) is bonded in a trigonal planar geometry to one Fe(1) and two equivalent Fe(4) atoms. In the fourth O site, O(4) is bonded in a trigonal planar geometry to one Fe(2) and two equivalent Fe(5) atoms. In the fifth O site, O(5) 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 sixth O site, O(6) is bonded in a trigonal planar geometry to one Fe(6) and two equivalent Fe(1) atoms. There are six inequivalent F sites. In the first F site, F(1) is bonded in a trigonal non-coplanar geometry to one Mg(1) and two equivalent Fe(1) atoms. In the second F site, F(2) is bonded in a distorted T-shaped geometry to one Fe(3) and two equivalent Fe(4) atoms. In the third F site, F(3) is bonded in a distorted trigonal non-coplanar geometry to two equivalent Mg(1) and one Fe(1) atom. In the fourth F site, F(4) is bonded in a distorted T-shaped geometry to one Fe(2) and two equivalent Fe(6) atoms. In the fifth F site, F(5) is bonded in a water-like geometry to two equivalent Fe(2) atoms. In the sixth F site, F(6) is bonded in a distorted T-shaped geometry to one Mg(1) and two equivalent Fe(3) atoms.