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(10), one O(12), one O(13), and one O(6) 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), one O(9), and one F(2) atom to form FeO5F octahedra that share corners with three equivalent Fe(7)O5 trigonal bipyramids,  an edgeedge with one Fe(4)O5F octahedra, and  an edgeedge with one Fe(2)O6 octahedra. In the second Fe site, Fe(2) is bonded to one O(1), one O(10), one O(12), one O(13), one O(4), and one O(6) atom to form edge-sharing FeO6 octahedra. 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  an edgeedge with one Fe(4)O5F octahedra and  an edgeedge with one Fe(2)O6 octahedra. In the fourth Fe site, Fe(4) is bonded to one O(11), one O(14), one O(2), one O(3), one O(8), and one F(2) atom to form FeO5F octahedra that share corners with three equivalent Fe(7)O5 trigonal bipyramids,  an edgeedge with one Fe(1)O5F octahedra, and  an edgeedge with one Fe(3)O5F octahedra. In the fifth Fe site, Fe(5) is bonded in a 5-coordinate geometry to one O(1), one O(10), one O(5), one O(6), and one O(9) atom. In the sixth Fe site, Fe(6) is bonded in a 5-coordinate geometry to one O(11), one O(14), one O(7), one O(8), and one F(1) atom. In the seventh Fe site, Fe(7) is bonded to one O(11), one O(3), one O(5), one O(8), and one O(9) atom to form distorted corner-sharing FeO5 trigonal bipyramids. The corner-sharing octahedral tilt angles range from 46-51°. In the eighth Fe site, Fe(8) is bonded in a 5-coordinate geometry to one O(10), one O(4), one O(6), one O(7), and one F(1) atom. There are fourteen inequivalent O sites. In the first O site, O(1) is bonded in a distorted 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 water-like geometry to one Fe(3) and one Fe(4) atom. In the third O site, O(3) is bonded in a distorted T-shaped geometry to one Fe(1), one Fe(4), and one Fe(7) atom. In the fourth O site, O(4) is bonded in a distorted trigonal planar geometry to one Fe(2), one Fe(3), and one Fe(8) atom. In the fifth O site, O(5) is bonded in a distorted trigonal planar geometry to one Fe(1), one Fe(5), and one Fe(7) atom. In the sixth O site, O(6) is bonded in a rectangular see-saw-like geometry to one Mg(1), one Fe(2), one Fe(5), and one Fe(8) atom. In the seventh O site, O(7) is bonded in a trigonal planar geometry to one Fe(3), one Fe(6), and one Fe(8) atom. In the eighth O site, O(8) is bonded in a trigonal planar geometry to one Fe(4), one Fe(6), and one Fe(7) atom. In the ninth O site, O(9) is bonded in a distorted trigonal planar geometry to one Fe(1), one Fe(5), and one Fe(7) atom. In the tenth O site, O(10) is bonded in a rectangular see-saw-like geometry to one Mg(1), one Fe(2), one Fe(5), and one Fe(8) atom. In the eleventh O site, O(11) is bonded in a trigonal planar geometry to one Fe(4), one Fe(6), and one Fe(7) atom. In the twelfth O site, O(12) is bonded in a T-shaped geometry to one Mg(1), one Fe(1), and one Fe(2) atom. In the thirteenth O site, O(13) is bonded in a T-shaped geometry to one Mg(1), one Fe(2), and one Fe(3) atom. In the fourteenth O site, O(14) is bonded in a distorted T-shaped 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 distorted trigonal planar geometry to one Fe(3), one Fe(6), and one Fe(8) atom. In the second F site, F(2) is bonded in an L-shaped geometry to one Fe(1) and one Fe(4) 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(10), one O(12), one O(13), and one O(6) atom. The Mg(1)-O(10) bond length is 1.98 Å. The Mg(1)-O(12) bond length is 1.90 Å. The Mg(1)-O(13) bond length is 1.91 Å. The Mg(1)-O(6) bond length is 1.98 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), one O(9), and one F(2) atom to form FeO5F octahedra that share corners with three equivalent Fe(7)O5 trigonal bipyramids,  an edgeedge with one Fe(4)O5F octahedra, and  an edgeedge with one Fe(2)O6 octahedra. The Fe(1)-O(1) bond length is 2.08 Å. The Fe(1)-O(12) bond length is 1.97 Å. The Fe(1)-O(3) bond length is 1.97 Å. The Fe(1)-O(5) bond length is 2.05 Å. The Fe(1)-O(9) bond length is 2.04 Å. The Fe(1)-F(2) bond length is 2.01 Å. In the second Fe site, Fe(2) is bonded to one O(1), one O(10), one O(12), one O(13), one O(4), and one O(6) atom to form edge-sharing FeO6 octahedra. The Fe(2)-O(1) bond length is 1.87 Å. The Fe(2)-O(10) bond length is 2.08 Å. The Fe(2)-O(12) bond length is 1.87 Å. The Fe(2)-O(13) bond length is 1.93 Å. The Fe(2)-O(4) bond length is 1.90 Å. The Fe(2)-O(6) bond length is 2.09 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  an edgeedge with one Fe(4)O5F octahedra and  an edgeedge with one Fe(2)O6 octahedra. The Fe(3)-O(13) bond length is 1.88 Å. The Fe(3)-O(14) bond length is 1.95 Å. The Fe(3)-O(2) bond length is 1.78 Å. The Fe(3)-O(4) bond length is 2.07 Å. The Fe(3)-O(7) bond length is 1.96 Å. The Fe(3)-F(1) bond length is 2.14 Å. In the fourth Fe site, Fe(4) is bonded to one O(11), one O(14), one O(2), one O(3), one O(8), and one F(2) atom to form FeO5F octahedra that share corners with three equivalent Fe(7)O5 trigonal bipyramids,  an edgeedge with one Fe(1)O5F octahedra, and  an edgeedge with one Fe(3)O5F octahedra. The Fe(4)-O(11) bond length is 2.03 Å. The Fe(4)-O(14) bond length is 2.07 Å. The Fe(4)-O(2) bond length is 1.94 Å. The Fe(4)-O(3) bond length is 1.99 Å. The Fe(4)-O(8) bond length is 2.04 Å. The Fe(4)-F(2) bond length is 1.98 Å. In the fifth Fe site, Fe(5) is bonded in a 5-coordinate geometry to one O(1), one O(10), one O(5), one O(6), and one O(9) atom. The Fe(5)-O(1) bond length is 1.90 Å. The Fe(5)-O(10) bond length is 2.08 Å. The Fe(5)-O(5) bond length is 1.95 Å. The Fe(5)-O(6) bond length is 2.06 Å. The Fe(5)-O(9) bond length is 1.94 Å. In the sixth Fe site, Fe(6) is bonded in a 5-coordinate geometry to one O(11), one O(14), one O(7), one O(8), and one F(1) atom. The Fe(6)-O(11) bond length is 1.98 Å. The Fe(6)-O(14) bond length is 1.92 Å. The Fe(6)-O(7) bond length is 1.97 Å. The Fe(6)-O(8) bond length is 1.96 Å. The Fe(6)-F(1) bond length is 2.17 Å. In the seventh Fe site, Fe(7) is bonded to one O(11), one O(3), one O(5), one O(8), and one O(9) atom to form distorted corner-sharing FeO5 trigonal bipyramids. The corner-sharing octahedral tilt angles range from 46-51°. The Fe(7)-O(11) bond length is 1.93 Å. The Fe(7)-O(3) bond length is 2.02 Å. The Fe(7)-O(5) bond length is 1.93 Å. The Fe(7)-O(8) bond length is 1.91 Å. The Fe(7)-O(9) bond length is 1.93 Å. In the eighth Fe site, Fe(8) is bonded in a 5-coordinate geometry to one O(10), one O(4), one O(6), one O(7), and one F(1) atom. The Fe(8)-O(10) bond length is 2.07 Å. The Fe(8)-O(4) bond length is 1.87 Å. The Fe(8)-O(6) bond length is 2.06 Å. The Fe(8)-O(7) bond length is 1.91 Å. The Fe(8)-F(1) bond length is 2.04 Å. There are fourteen inequivalent O sites. In the first O site, O(1) is bonded in a distorted 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 water-like geometry to one Fe(3) and one Fe(4) atom. In the third O site, O(3) is bonded in a distorted T-shaped geometry to one Fe(1), one Fe(4), and one Fe(7) atom. In the fourth O site, O(4) is bonded in a distorted trigonal planar geometry to one Fe(2), one Fe(3), and one Fe(8) atom. In the fifth O site, O(5) is bonded in a distorted trigonal planar geometry to one Fe(1), one Fe(5), and one Fe(7) atom. In the sixth O site, O(6) is bonded in a rectangular see-saw-like geometry to one Mg(1), one Fe(2), one Fe(5), and one Fe(8) atom. In the seventh O site, O(7) is bonded in a trigonal planar geometry to one Fe(3), one Fe(6), and one Fe(8) atom. In the eighth O site, O(8) is bonded in a trigonal planar geometry to one Fe(4), one Fe(6), and one Fe(7) atom. In the ninth O site, O(9) is bonded in a distorted trigonal planar geometry to one Fe(1), one Fe(5), and one Fe(7) atom. In the tenth O site, O(10) is bonded in a rectangular see-saw-like geometry to one Mg(1), one Fe(2), one Fe(5), and one Fe(8) atom. In the eleventh O site, O(11) is bonded in a trigonal planar geometry to one Fe(4), one Fe(6), and one Fe(7) atom. In the twelfth O site, O(12) is bonded in a T-shaped geometry to one Mg(1), one Fe(1), and one Fe(2) atom. In the thirteenth O site, O(13) is bonded in a T-shaped geometry to one Mg(1), one Fe(2), and one Fe(3) atom. In the fourteenth O site, O(14) is bonded in a distorted T-shaped 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 distorted trigonal planar geometry to one Fe(3), one Fe(6), and one Fe(8) atom. In the second F site, F(2) is bonded in an L-shaped geometry to one Fe(1) and one Fe(4) atom.