MgFe10O9F11 is zeta iron carbide-derived structured and crystallizes in the monoclinic Pm space group. Mg(1) is bonded in a 4-coordinate geometry to one O(3), two equivalent O(6), and two equivalent F(1) atoms. There are six inequivalent Fe sites. In the first Fe site, Fe(1) is bonded to one O(2), one O(5), one F(1), one F(2), one F(4), and one F(5) atom to form FeO2F4 octahedra that share corners with four equivalent Fe(5)O3F3 octahedra, corners with four equivalent Fe(4)O4F2 octahedra, and  an edgeedge with one Fe(3)O2F4 octahedra. The corner-sharing octahedral tilt angles range from 45-53°. In the second Fe site, Fe(2) is bonded in a 4-coordinate geometry to one O(3), one O(6), and two equivalent F(4) atoms. In the third Fe site, Fe(3) is bonded to one O(1), one O(4), one F(2), one F(3), one F(5), and one F(6) atom to form FeO2F4 octahedra that share corners with four equivalent Fe(5)O3F3 octahedra, corners with four equivalent Fe(6)O3F3 octahedra,  an edgeedge with one Fe(1)O2F4 octahedra, and  an edgeedge with one Fe(3)O2F4 octahedra. The corner-sharing octahedral tilt angles range from 40-63°. In the fourth Fe site, Fe(4) is bonded to one O(2), one O(3), one O(5), one O(6), one F(1), and one F(4) atom to form distorted FeO4F2 octahedra that share corners with four equivalent Fe(1)O2F4 octahedra,  an edgeedge with one Fe(5)O3F3 octahedra, and  an edgeedge with one Fe(4)O4F2 octahedra. The corner-sharing octahedral tilt angles range from 45-48°. In the fifth Fe site, Fe(5) is bonded to one O(2), one O(4), one O(5), one F(2), one F(3), and one F(5) atom to form FeO3F3 octahedra that share corners with four equivalent Fe(1)O2F4 octahedra, corners with four equivalent Fe(3)O2F4 octahedra,  an edgeedge with one Fe(6)O3F3 octahedra, and  an edgeedge with one Fe(4)O4F2 octahedra. The corner-sharing octahedral tilt angles range from 43-53°. In the sixth Fe site, Fe(6) is bonded to one O(1), two equivalent O(4), one F(6), and two equivalent F(3) atoms to form FeO3F3 octahedra that share corners with eight equivalent Fe(3)O2F4 octahedra and edges with two equivalent Fe(5)O3F3 octahedra. The corner-sharing octahedral tilt angles range from 40-63°. There are six inequivalent O sites. In the first O site, O(1) is bonded in a distorted T-shaped geometry to one Fe(6) and two equivalent Fe(3) atoms. In the second O site, O(2) is bonded in a distorted trigonal planar geometry to one Fe(1), one Fe(4), and one Fe(5) atom. In the third O site, O(3) is bonded in a 4-coordinate geometry to one Mg(1), one Fe(2), and two equivalent Fe(4) atoms. In the fourth O site, O(4) is bonded in a trigonal planar geometry to one Fe(3), one Fe(5), and one Fe(6) atom. In the fifth O site, O(5) is bonded in a distorted trigonal planar geometry to one Fe(1), one Fe(4), and one Fe(5) atom. In the sixth O site, O(6) is bonded in a 5-coordinate geometry to two equivalent Mg(1), 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 3-coordinate geometry to one Mg(1), one Fe(1), and one Fe(4) atom. In the second F site, F(2) is bonded in a distorted trigonal planar geometry to one Fe(1), one Fe(3), and one Fe(5) atom. In the third F site, F(3) is bonded in a distorted trigonal planar geometry to one Fe(3), one Fe(5), and one Fe(6) atom. In the fourth F site, F(4) is bonded in a trigonal planar geometry to one Fe(1), one Fe(2), and one Fe(4) atom. In the fifth F site, F(5) is bonded in a distorted trigonal planar geometry to one Fe(1), one Fe(3), and one Fe(5) atom. In the sixth F site, F(6) is bonded in a 3-coordinate geometry to one Fe(6) and two equivalent Fe(3) atoms.
MgFe10O9F11 is zeta iron carbide-derived structured and crystallizes in the monoclinic Pm space group. Mg(1) is bonded in a 4-coordinate geometry to one O(3), two equivalent O(6), and two equivalent F(1) atoms. The Mg(1)-O(3) bond length is 2.06 Å. There is one shorter (2.12 Å) and one longer (2.69 Å) Mg(1)-O(6) bond length. Both Mg(1)-F(1) bond lengths are 1.90 Å. There are six inequivalent Fe sites. In the first Fe site, Fe(1) is bonded to one O(2), one O(5), one F(1), one F(2), one F(4), and one F(5) atom to form FeO2F4 octahedra that share corners with four equivalent Fe(5)O3F3 octahedra, corners with four equivalent Fe(4)O4F2 octahedra, and  an edgeedge with one Fe(3)O2F4 octahedra. The corner-sharing octahedral tilt angles range from 45-53°. The Fe(1)-O(2) bond length is 1.92 Å. The Fe(1)-O(5) bond length is 1.91 Å. The Fe(1)-F(1) bond length is 2.09 Å. The Fe(1)-F(2) bond length is 2.02 Å. The Fe(1)-F(4) bond length is 2.12 Å. The Fe(1)-F(5) bond length is 2.04 Å. In the second Fe site, Fe(2) is bonded in a 4-coordinate geometry to one O(3), one O(6), and two equivalent F(4) atoms. The Fe(2)-O(3) bond length is 2.03 Å. The Fe(2)-O(6) bond length is 2.04 Å. Both Fe(2)-F(4) bond lengths are 1.99 Å. In the third Fe site, Fe(3) is bonded to one O(1), one O(4), one F(2), one F(3), one F(5), and one F(6) atom to form FeO2F4 octahedra that share corners with four equivalent Fe(5)O3F3 octahedra, corners with four equivalent Fe(6)O3F3 octahedra,  an edgeedge with one Fe(1)O2F4 octahedra, and  an edgeedge with one Fe(3)O2F4 octahedra. The corner-sharing octahedral tilt angles range from 40-63°. The Fe(3)-O(1) bond length is 1.95 Å. The Fe(3)-O(4) bond length is 1.93 Å. The Fe(3)-F(2) bond length is 2.20 Å. The Fe(3)-F(3) bond length is 2.04 Å. The Fe(3)-F(5) bond length is 2.23 Å. The Fe(3)-F(6) bond length is 2.10 Å. In the fourth Fe site, Fe(4) is bonded to one O(2), one O(3), one O(5), one O(6), one F(1), and one F(4) atom to form distorted FeO4F2 octahedra that share corners with four equivalent Fe(1)O2F4 octahedra,  an edgeedge with one Fe(5)O3F3 octahedra, and  an edgeedge with one Fe(4)O4F2 octahedra. The corner-sharing octahedral tilt angles range from 45-48°. The Fe(4)-O(2) bond length is 2.00 Å. The Fe(4)-O(3) bond length is 2.26 Å. The Fe(4)-O(5) bond length is 2.01 Å. The Fe(4)-O(6) bond length is 2.25 Å. The Fe(4)-F(1) bond length is 2.25 Å. The Fe(4)-F(4) bond length is 2.07 Å. In the fifth Fe site, Fe(5) is bonded to one O(2), one O(4), one O(5), one F(2), one F(3), and one F(5) atom to form FeO3F3 octahedra that share corners with four equivalent Fe(1)O2F4 octahedra, corners with four equivalent Fe(3)O2F4 octahedra,  an edgeedge with one Fe(6)O3F3 octahedra, and  an edgeedge with one Fe(4)O4F2 octahedra. The corner-sharing octahedral tilt angles range from 43-53°. The Fe(5)-O(2) bond length is 1.94 Å. The Fe(5)-O(4) bond length is 1.92 Å. The Fe(5)-O(5) bond length is 1.97 Å. The Fe(5)-F(2) bond length is 2.20 Å. The Fe(5)-F(3) bond length is 2.17 Å. The Fe(5)-F(5) bond length is 2.18 Å. In the sixth Fe site, Fe(6) is bonded to one O(1), two equivalent O(4), one F(6), and two equivalent F(3) atoms to form FeO3F3 octahedra that share corners with eight equivalent Fe(3)O2F4 octahedra and edges with two equivalent Fe(5)O3F3 octahedra. The corner-sharing octahedral tilt angles range from 40-63°. The Fe(6)-O(1) bond length is 1.92 Å. Both Fe(6)-O(4) bond lengths are 1.94 Å. The Fe(6)-F(6) bond length is 2.27 Å. Both Fe(6)-F(3) bond lengths are 2.13 Å. There are six inequivalent O sites. In the first O site, O(1) is bonded in a distorted T-shaped geometry to one Fe(6) and two equivalent Fe(3) atoms. In the second O site, O(2) is bonded in a distorted trigonal planar geometry to one Fe(1), one Fe(4), and one Fe(5) atom. In the third O site, O(3) is bonded in a 4-coordinate geometry to one Mg(1), one Fe(2), and two equivalent Fe(4) atoms. In the fourth O site, O(4) is bonded in a trigonal planar geometry to one Fe(3), one Fe(5), and one Fe(6) atom. In the fifth O site, O(5) is bonded in a distorted trigonal planar geometry to one Fe(1), one Fe(4), and one Fe(5) atom. In the sixth O site, O(6) is bonded in a 5-coordinate geometry to two equivalent Mg(1), 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 3-coordinate geometry to one Mg(1), one Fe(1), and one Fe(4) atom. In the second F site, F(2) is bonded in a distorted trigonal planar geometry to one Fe(1), one Fe(3), and one Fe(5) atom. In the third F site, F(3) is bonded in a distorted trigonal planar geometry to one Fe(3), one Fe(5), and one Fe(6) atom. In the fourth F site, F(4) is bonded in a trigonal planar geometry to one Fe(1), one Fe(2), and one Fe(4) atom. In the fifth F site, F(5) is bonded in a distorted trigonal planar geometry to one Fe(1), one Fe(3), and one Fe(5) atom. In the sixth F site, F(6) is bonded in a 3-coordinate geometry to one Fe(6) and two equivalent Fe(3) atoms.