MgFe8(O7F)2 crystallizes in the triclinic P1 space group. Mg(1) is bonded in a distorted rectangular see-saw-like geometry to one O(13), one O(4), one O(6), and one O(7) atom. There are eight inequivalent Fe sites. In the first Fe site, Fe(1) is bonded to one O(1), one O(12), one O(3), one O(5), and one F(2) atom to form distorted FeO4F trigonal bipyramids that share corners with three equivalent Fe(7)O5F octahedra and corners with three equivalent Fe(5)O6 octahedra. The corner-sharing octahedral tilt angles range from 45-57°. In the second Fe site, Fe(2) is bonded in a 5-coordinate geometry to one O(1), one O(10), one O(12), one O(13), and one O(4) atom. In the third Fe site, Fe(3) is bonded to one O(13), one O(14), one O(2), one O(4), one O(7), and one F(1) atom to form FeO5F octahedra that share corners with three equivalent Fe(6)O5 square pyramids and corners with three equivalent Fe(8)O4F trigonal bipyramids. In the fourth Fe site, Fe(4) is bonded in a 5-coordinate geometry to one O(11), one O(14), one O(2), one O(3), and one F(2) atom. In the fifth Fe site, Fe(5) is bonded to one O(1), one O(10), one O(12), one O(5), one O(6), and one O(9) atom to form FeO6 octahedra that share corners with three equivalent Fe(1)O4F trigonal bipyramids,  an edgeedge with one Fe(7)O5F octahedra, and  an edgeedge with one Fe(8)O4F trigonal bipyramid. In the sixth Fe site, Fe(6) is bonded to one O(11), one O(14), one O(2), one O(7), and one O(8) atom to form a mixture of corner and edge-sharing FeO5 square pyramids. The corner-sharing octahedral tilt angles range from 42-46°. In the seventh Fe site, Fe(7) is bonded to one O(11), one O(3), one O(5), one O(8), one O(9), and one F(2) atom to form FeO5F octahedra that share corners with three equivalent Fe(1)O4F trigonal bipyramids,  an edgeedge with one Fe(5)O6 octahedra, and  an edgeedge with one Fe(6)O5 square pyramid. In the eighth Fe site, Fe(8) is bonded to one O(10), one O(13), one O(4), one O(6), and one F(1) atom to form distorted FeO4F trigonal bipyramids that share corners with three equivalent Fe(3)O5F octahedra and  an edgeedge with one Fe(5)O6 octahedra. The corner-sharing octahedral tilt angles range from 41-47°. There are fourteen inequivalent O sites. In the first O site, O(1) is bonded in a trigonal planar geometry to one Fe(1), one Fe(2), and one Fe(5) atom. In the second O site, O(2) is bonded in a distorted trigonal planar geometry to one Fe(3), one Fe(4), and one Fe(6) atom. In the third O site, O(3) is bonded in a trigonal planar geometry to one Fe(1), one Fe(4), and one Fe(7) atom. In the fourth O site, O(4) is bonded in a 4-coordinate geometry to one Mg(1), one Fe(2), one Fe(3), and one Fe(8) atom. In the fifth O site, O(5) is bonded in a distorted T-shaped geometry to one Fe(1), one Fe(5), and one Fe(7) atom. In the sixth O site, O(6) is bonded in a T-shaped geometry to one Mg(1), one Fe(5), and one Fe(8) atom. In the seventh O site, O(7) is bonded in a distorted T-shaped geometry to one Mg(1), one Fe(3), and one Fe(6) atom. In the eighth O site, O(8) is bonded in a water-like geometry to one Fe(6) and one Fe(7) atom. In the ninth O site, O(9) is bonded in a water-like geometry to one Fe(5) and one Fe(7) atom. In the tenth O site, O(10) is bonded in a distorted trigonal planar geometry to one Fe(2), one Fe(5), and one Fe(8) atom. In the eleventh O site, O(11) is bonded in a distorted T-shaped geometry to one Fe(4), one Fe(6), and one Fe(7) atom. In the twelfth O site, O(12) is bonded in a trigonal planar geometry to one Fe(1), one Fe(2), and one Fe(5) atom. In the thirteenth O site, O(13) is bonded in a distorted trigonal pyramidal geometry to one Mg(1), one Fe(2), one Fe(3), and one Fe(8) atom. In the fourteenth O site, O(14) is bonded in a trigonal planar geometry to one Fe(3), one Fe(4), and one Fe(6) atom. There are two inequivalent F sites. In the first F site, F(1) is bonded in a bent 150 degrees geometry to one Fe(3) and one Fe(8) atom. In the second F site, F(2) is bonded in a trigonal planar geometry to one Fe(1), one Fe(4), and one Fe(7) atom.
MgFe8(O7F)2 crystallizes in the triclinic P1 space group. Mg(1) is bonded in a distorted rectangular see-saw-like geometry to one O(13), one O(4), one O(6), and one O(7) atom. The Mg(1)-O(13) bond length is 2.04 Å. The Mg(1)-O(4) bond length is 2.05 Å. The Mg(1)-O(6) bond length is 1.90 Å. The Mg(1)-O(7) bond length is 1.92 Å. There are eight inequivalent Fe sites. In the first Fe site, Fe(1) is bonded to one O(1), one O(12), one O(3), one O(5), and one F(2) atom to form distorted FeO4F trigonal bipyramids that share corners with three equivalent Fe(7)O5F octahedra and corners with three equivalent Fe(5)O6 octahedra. The corner-sharing octahedral tilt angles range from 45-57°. The Fe(1)-O(1) bond length is 1.95 Å. The Fe(1)-O(12) bond length is 1.96 Å. The Fe(1)-O(3) bond length is 1.94 Å. The Fe(1)-O(5) bond length is 1.92 Å. The Fe(1)-F(2) bond length is 2.09 Å. In the second Fe site, Fe(2) is bonded in a 5-coordinate geometry to one O(1), one O(10), one O(12), one O(13), and one O(4) atom. The Fe(2)-O(1) bond length is 1.94 Å. The Fe(2)-O(10) bond length is 1.86 Å. The Fe(2)-O(12) bond length is 1.95 Å. The Fe(2)-O(13) bond length is 2.12 Å. The Fe(2)-O(4) bond length is 2.14 Å. In the third Fe site, Fe(3) is bonded to one O(13), one O(14), one O(2), one O(4), one O(7), and one F(1) atom to form FeO5F octahedra that share corners with three equivalent Fe(6)O5 square pyramids and corners with three equivalent Fe(8)O4F trigonal bipyramids. The Fe(3)-O(13) bond length is 2.17 Å. The Fe(3)-O(14) bond length is 1.95 Å. The Fe(3)-O(2) bond length is 1.93 Å. The Fe(3)-O(4) bond length is 2.17 Å. The Fe(3)-O(7) bond length is 2.01 Å. The Fe(3)-F(1) bond length is 2.09 Å. In the fourth Fe site, Fe(4) is bonded in a 5-coordinate geometry to one O(11), one O(14), one O(2), one O(3), and one F(2) atom. The Fe(4)-O(11) bond length is 1.94 Å. The Fe(4)-O(14) bond length is 2.00 Å. The Fe(4)-O(2) bond length is 1.99 Å. The Fe(4)-O(3) bond length is 1.96 Å. The Fe(4)-F(2) bond length is 2.11 Å. In the fifth Fe site, Fe(5) is bonded to one O(1), one O(10), one O(12), one O(5), one O(6), and one O(9) atom to form FeO6 octahedra that share corners with three equivalent Fe(1)O4F trigonal bipyramids,  an edgeedge with one Fe(7)O5F octahedra, and  an edgeedge with one Fe(8)O4F trigonal bipyramid. The Fe(5)-O(1) bond length is 1.97 Å. The Fe(5)-O(10) bond length is 2.08 Å. The Fe(5)-O(12) bond length is 1.97 Å. The Fe(5)-O(5) bond length is 2.01 Å. The Fe(5)-O(6) bond length is 1.88 Å. The Fe(5)-O(9) bond length is 1.87 Å. In the sixth Fe site, Fe(6) is bonded to one O(11), one O(14), one O(2), one O(7), and one O(8) atom to form a mixture of corner and edge-sharing FeO5 square pyramids. The corner-sharing octahedral tilt angles range from 42-46°. The Fe(6)-O(11) bond length is 2.04 Å. The Fe(6)-O(14) bond length is 1.94 Å. The Fe(6)-O(2) bond length is 1.94 Å. The Fe(6)-O(7) bond length is 1.88 Å. The Fe(6)-O(8) bond length is 1.89 Å. In the seventh Fe site, Fe(7) is bonded to one O(11), one O(3), one O(5), one O(8), one O(9), and one F(2) atom to form FeO5F octahedra that share corners with three equivalent Fe(1)O4F trigonal bipyramids,  an edgeedge with one Fe(5)O6 octahedra, and  an edgeedge with one Fe(6)O5 square pyramid. The Fe(7)-O(11) bond length is 1.98 Å. The Fe(7)-O(3) bond length is 1.93 Å. The Fe(7)-O(5) bond length is 1.95 Å. The Fe(7)-O(8) bond length is 1.81 Å. The Fe(7)-O(9) bond length is 1.84 Å. The Fe(7)-F(2) bond length is 2.09 Å. In the eighth Fe site, Fe(8) is bonded to one O(10), one O(13), one O(4), one O(6), and one F(1) atom to form distorted FeO4F trigonal bipyramids that share corners with three equivalent Fe(3)O5F octahedra and  an edgeedge with one Fe(5)O6 octahedra. The corner-sharing octahedral tilt angles range from 41-47°. The Fe(8)-O(10) bond length is 1.86 Å. The Fe(8)-O(13) bond length is 2.02 Å. The Fe(8)-O(4) bond length is 2.01 Å. The Fe(8)-O(6) bond length is 1.98 Å. The Fe(8)-F(1) bond length is 1.93 Å. There are fourteen inequivalent O sites. In the first O site, O(1) is bonded in a trigonal planar geometry to one Fe(1), one Fe(2), and one Fe(5) atom. In the second O site, O(2) is bonded in a distorted trigonal planar geometry to one Fe(3), one Fe(4), and one Fe(6) atom. In the third O site, O(3) is bonded in a trigonal planar geometry to one Fe(1), one Fe(4), and one Fe(7) atom. In the fourth O site, O(4) is bonded in a 4-coordinate geometry to one Mg(1), one Fe(2), one Fe(3), and one Fe(8) atom. In the fifth O site, O(5) is bonded in a distorted T-shaped geometry to one Fe(1), one Fe(5), and one Fe(7) atom. In the sixth O site, O(6) is bonded in a T-shaped geometry to one Mg(1), one Fe(5), and one Fe(8) atom. In the seventh O site, O(7) is bonded in a distorted T-shaped geometry to one Mg(1), one Fe(3), and one Fe(6) atom. In the eighth O site, O(8) is bonded in a water-like geometry to one Fe(6) and one Fe(7) atom. In the ninth O site, O(9) is bonded in a water-like geometry to one Fe(5) and one Fe(7) atom. In the tenth O site, O(10) is bonded in a distorted trigonal planar geometry to one Fe(2), one Fe(5), and one Fe(8) atom. In the eleventh O site, O(11) is bonded in a distorted T-shaped geometry to one Fe(4), one Fe(6), and one Fe(7) atom. In the twelfth O site, O(12) is bonded in a trigonal planar geometry to one Fe(1), one Fe(2), and one Fe(5) atom. In the thirteenth O site, O(13) is bonded in a distorted trigonal pyramidal geometry to one Mg(1), one Fe(2), one Fe(3), and one Fe(8) atom. In the fourteenth O site, O(14) is bonded in a trigonal planar geometry to one Fe(3), one Fe(4), and one Fe(6) atom. There are two inequivalent F sites. In the first F site, F(1) is bonded in a bent 150 degrees geometry to one Fe(3) and one Fe(8) atom. In the second F site, F(2) is bonded in a trigonal planar geometry to one Fe(1), one Fe(4), and one Fe(7) atom.