MgFe8(OF)8 crystallizes in the triclinic P1 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(3)O3F2 square pyramids, edges with two equivalent Mg(1)O2F4 octahedra, and edges with two equivalent Fe(7)O3F3 octahedra. There are eight inequivalent Fe sites. In the first Fe site, Fe(1) is bonded to one O(3), two equivalent O(2), one F(7), and two equivalent F(8) atoms to form FeO3F3 octahedra that share corners with two equivalent Fe(4)O3F3 octahedra, corners with two equivalent Fe(7)O3F3 octahedra, corners with two equivalent Fe(8)O3F3 octahedra, corners with two equivalent Fe(3)O3F2 square pyramids, and edges with two equivalent Fe(1)O3F3 octahedra. The corner-sharing octahedral tilt angles range from 45-53°. In the second Fe site, Fe(2) is bonded to one O(4), one O(7), two equivalent O(1), and two equivalent O(8) atoms to form FeO6 octahedra that share corners with two equivalent Fe(4)O3F3 octahedra, corners with two equivalent Fe(7)O3F3 octahedra, corners with two equivalent Fe(8)O3F3 octahedra, corners with two equivalent Fe(3)O3F2 square pyramids, and edges with two equivalent Fe(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 51-56°. In the third Fe site, Fe(3) is bonded to one O(1), two equivalent O(3), and two equivalent F(1) atoms to form distorted FeO3F2 square pyramids that share corners with two equivalent Mg(1)O2F4 octahedra, corners with two equivalent Fe(1)O3F3 octahedra, corners with two equivalent Fe(2)O6 octahedra, and edges with two equivalent Fe(3)O3F2 square pyramids. The corner-sharing octahedral tilt angles range from 50-63°. In the fourth Fe site, Fe(4) is bonded to one O(2), two equivalent O(4), one F(4), and two equivalent F(2) atoms to form distorted FeO3F3 octahedra that share corners with two equivalent Fe(1)O3F3 octahedra, corners with two equivalent Fe(2)O6 octahedra, and edges with two equivalent Fe(4)O3F3 octahedra. The corner-sharing octahedral tilt angles range from 53-56°. In the fifth Fe site, Fe(5) is bonded in a 5-coordinate geometry to one O(6), two equivalent O(5), and two equivalent F(4) atoms. In the sixth Fe site, Fe(6) is bonded in a 6-coordinate geometry to one F(2), one F(6), two equivalent F(3), and two equivalent F(5) atoms. In the seventh Fe site, Fe(7) is bonded to one O(5), two equivalent O(7), one F(8), and two equivalent F(6) atoms to form distorted FeO3F3 octahedra that share corners with two equivalent Fe(1)O3F3 octahedra, corners with two equivalent Fe(2)O6 octahedra, edges with two equivalent Mg(1)O2F4 octahedra, and edges with two equivalent Fe(7)O3F3 octahedra. The corner-sharing octahedral tilt angles range from 45-56°. In the eighth Fe site, Fe(8) is bonded to one O(8), two equivalent O(6), one F(5), and two equivalent F(7) atoms to form FeO3F3 octahedra that share corners with two equivalent Fe(1)O3F3 octahedra, corners with two equivalent Fe(2)O6 octahedra, and edges with two equivalent Fe(8)O3F3 octahedra. The corner-sharing octahedral tilt angles range from 48-52°. There are eight inequivalent O sites. In the first O site, O(1) is bonded in a distorted trigonal planar geometry to one Fe(3) and two equivalent Fe(2) atoms. In the second O site, O(2) is bonded in a trigonal planar geometry to one Fe(4) and two equivalent Fe(1) atoms. In the third O site, O(3) is bonded in a trigonal planar geometry to one Fe(1) and two equivalent Fe(3) atoms. In the fourth O site, O(4) is bonded in a trigonal planar geometry to one Fe(2) and two equivalent Fe(4) atoms. In the fifth O site, O(5) is bonded in a 5-coordinate geometry to two equivalent Mg(1), one Fe(7), and two equivalent Fe(5) atoms. In the sixth O site, O(6) is bonded in a trigonal planar geometry to one Fe(5) and two equivalent Fe(8) atoms. In the seventh O site, O(7) is bonded in a trigonal planar geometry to one Fe(2) and two equivalent Fe(7) atoms. In the eighth O site, O(8) is bonded in a trigonal planar geometry to one Fe(8) and two equivalent Fe(2) atoms. There are eight inequivalent F sites. In the first F site, F(1) is bonded in a distorted trigonal non-coplanar geometry to one Mg(1) and two equivalent Fe(3) atoms. In the second F site, F(2) is bonded in a 3-coordinate geometry to one Fe(6) and two equivalent Fe(4) atoms. In the third F site, F(3) is bonded in a distorted rectangular see-saw-like geometry to two equivalent Mg(1) and two equivalent Fe(6) atoms. In the fourth F site, F(4) is bonded in a distorted T-shaped geometry to one Fe(4) and two equivalent Fe(5) atoms. In the fifth F site, F(5) is bonded in a trigonal planar geometry to one Fe(8) and two equivalent Fe(6) atoms. In the sixth F site, F(6) is bonded in a rectangular see-saw-like geometry to one Mg(1), one Fe(6), and two equivalent Fe(7) atoms. In the seventh F site, F(7) is bonded in a distorted T-shaped geometry to one Fe(1) and two equivalent Fe(8) atoms. In the eighth F site, F(8) is bonded in a distorted T-shaped geometry to one Fe(7) and two equivalent Fe(1) atoms.
MgFe8(OF)8 crystallizes in the triclinic P1 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(3)O3F2 square pyramids, edges with two equivalent Mg(1)O2F4 octahedra, and edges with two equivalent Fe(7)O3F3 octahedra. Both Mg(1)-O(5) bond lengths are 2.04 Å. The Mg(1)-F(1) bond length is 1.92 Å. The Mg(1)-F(6) bond length is 1.95 Å. There is one shorter (2.17 Å) and one longer (2.20 Å) Mg(1)-F(3) bond length. There are eight inequivalent Fe sites. In the first Fe site, Fe(1) is bonded to one O(3), two equivalent O(2), one F(7), and two equivalent F(8) atoms to form FeO3F3 octahedra that share corners with two equivalent Fe(4)O3F3 octahedra, corners with two equivalent Fe(7)O3F3 octahedra, corners with two equivalent Fe(8)O3F3 octahedra, corners with two equivalent Fe(3)O3F2 square pyramids, and edges with two equivalent Fe(1)O3F3 octahedra. The corner-sharing octahedral tilt angles range from 45-53°. The Fe(1)-O(3) bond length is 1.93 Å. Both Fe(1)-O(2) bond lengths are 1.94 Å. The Fe(1)-F(7) bond length is 2.07 Å. There is one shorter (2.22 Å) and one longer (2.23 Å) Fe(1)-F(8) bond length. In the second Fe site, Fe(2) is bonded to one O(4), one O(7), two equivalent O(1), and two equivalent O(8) atoms to form FeO6 octahedra that share corners with two equivalent Fe(4)O3F3 octahedra, corners with two equivalent Fe(7)O3F3 octahedra, corners with two equivalent Fe(8)O3F3 octahedra, corners with two equivalent Fe(3)O3F2 square pyramids, and edges with two equivalent Fe(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 51-56°. The Fe(2)-O(4) bond length is 2.04 Å. The Fe(2)-O(7) bond length is 2.13 Å. There is one shorter (2.03 Å) and one longer (2.04 Å) Fe(2)-O(1) bond length. There is one shorter (1.99 Å) and one longer (2.00 Å) Fe(2)-O(8) bond length. In the third Fe site, Fe(3) is bonded to one O(1), two equivalent O(3), and two equivalent F(1) atoms to form distorted FeO3F2 square pyramids that share corners with two equivalent Mg(1)O2F4 octahedra, corners with two equivalent Fe(1)O3F3 octahedra, corners with two equivalent Fe(2)O6 octahedra, and edges with two equivalent Fe(3)O3F2 square pyramids. The corner-sharing octahedral tilt angles range from 50-63°. The Fe(3)-O(1) bond length is 1.81 Å. There is one shorter (1.92 Å) and one longer (1.93 Å) Fe(3)-O(3) bond length. There is one shorter (2.20 Å) and one longer (2.21 Å) Fe(3)-F(1) bond length. In the fourth Fe site, Fe(4) is bonded to one O(2), two equivalent O(4), one F(4), and two equivalent F(2) atoms to form distorted FeO3F3 octahedra that share corners with two equivalent Fe(1)O3F3 octahedra, corners with two equivalent Fe(2)O6 octahedra, and edges with two equivalent Fe(4)O3F3 octahedra. The corner-sharing octahedral tilt angles range from 53-56°. The Fe(4)-O(2) bond length is 1.98 Å. Both Fe(4)-O(4) bond lengths are 1.90 Å. The Fe(4)-F(4) bond length is 2.15 Å. There is one shorter (2.26 Å) and one longer (2.29 Å) Fe(4)-F(2) bond length. In the fifth Fe site, Fe(5) is bonded in a 5-coordinate geometry to one O(6), two equivalent O(5), and two equivalent F(4) atoms. The Fe(5)-O(6) bond length is 1.90 Å. There is one shorter (2.28 Å) and one longer (2.35 Å) Fe(5)-O(5) bond length. Both Fe(5)-F(4) bond lengths are 2.14 Å. In the sixth Fe site, Fe(6) is bonded in a 6-coordinate geometry to one F(2), one F(6), two equivalent F(3), and two equivalent F(5) atoms. The Fe(6)-F(2) bond length is 1.98 Å. The Fe(6)-F(6) bond length is 2.33 Å. Both Fe(6)-F(3) bond lengths are 2.24 Å. Both Fe(6)-F(5) bond lengths are 2.01 Å. In the seventh Fe site, Fe(7) is bonded to one O(5), two equivalent O(7), one F(8), and two equivalent F(6) atoms to form distorted FeO3F3 octahedra that share corners with two equivalent Fe(1)O3F3 octahedra, corners with two equivalent Fe(2)O6 octahedra, edges with two equivalent Mg(1)O2F4 octahedra, and edges with two equivalent Fe(7)O3F3 octahedra. The corner-sharing octahedral tilt angles range from 45-56°. The Fe(7)-O(5) bond length is 2.08 Å. Both Fe(7)-O(7) bond lengths are 1.88 Å. The Fe(7)-F(8) bond length is 2.16 Å. There is one shorter (2.32 Å) and one longer (2.33 Å) Fe(7)-F(6) bond length. In the eighth Fe site, Fe(8) is bonded to one O(8), two equivalent O(6), one F(5), and two equivalent F(7) atoms to form FeO3F3 octahedra that share corners with two equivalent Fe(1)O3F3 octahedra, corners with two equivalent Fe(2)O6 octahedra, and edges with two equivalent Fe(8)O3F3 octahedra. The corner-sharing octahedral tilt angles range from 48-52°. The Fe(8)-O(8) bond length is 1.86 Å. Both Fe(8)-O(6) bond lengths are 1.94 Å. The Fe(8)-F(5) bond length is 2.15 Å. Both Fe(8)-F(7) bond lengths are 2.18 Å. There are eight inequivalent O sites. In the first O site, O(1) is bonded in a distorted trigonal planar geometry to one Fe(3) and two equivalent Fe(2) atoms. In the second O site, O(2) is bonded in a trigonal planar geometry to one Fe(4) and two equivalent Fe(1) atoms. In the third O site, O(3) is bonded in a trigonal planar geometry to one Fe(1) and two equivalent Fe(3) atoms. In the fourth O site, O(4) is bonded in a trigonal planar geometry to one Fe(2) and two equivalent Fe(4) atoms. In the fifth O site, O(5) is bonded in a 5-coordinate geometry to two equivalent Mg(1), one Fe(7), and two equivalent Fe(5) atoms. In the sixth O site, O(6) is bonded in a trigonal planar geometry to one Fe(5) and two equivalent Fe(8) atoms. In the seventh O site, O(7) is bonded in a trigonal planar geometry to one Fe(2) and two equivalent Fe(7) atoms. In the eighth O site, O(8) is bonded in a trigonal planar geometry to one Fe(8) and two equivalent Fe(2) atoms. There are eight inequivalent F sites. In the first F site, F(1) is bonded in a distorted trigonal non-coplanar geometry to one Mg(1) and two equivalent Fe(3) atoms. In the second F site, F(2) is bonded in a 3-coordinate geometry to one Fe(6) and two equivalent Fe(4) atoms. In the third F site, F(3) is bonded in a distorted rectangular see-saw-like geometry to two equivalent Mg(1) and two equivalent Fe(6) atoms. In the fourth F site, F(4) is bonded in a distorted T-shaped geometry to one Fe(4) and two equivalent Fe(5) atoms. In the fifth F site, F(5) is bonded in a trigonal planar geometry to one Fe(8) and two equivalent Fe(6) atoms. In the sixth F site, F(6) is bonded in a rectangular see-saw-like geometry to one Mg(1), one Fe(6), and two equivalent Fe(7) atoms. In the seventh F site, F(7) is bonded in a distorted T-shaped geometry to one Fe(1) and two equivalent Fe(8) atoms. In the eighth F site, F(8) is bonded in a distorted T-shaped geometry to one Fe(7) and two equivalent Fe(1) atoms.