MgFe6(OF)6 crystallizes in the triclinic P1 space group. Mg(1) is bonded to one O(4), one O(5), one O(6), one F(1), one F(3), and one F(5) atom to form MgO3F3 octahedra that share corners with two equivalent Fe(5)O3F3 octahedra,  an edgeedge with one Fe(3)O2F4 octahedra,  an edgeedge with one Fe(2)O3F3 octahedra, and edges with two equivalent Fe(6)O2F4 octahedra. The corner-sharing octahedral tilt angles range from 49-55°. There are six inequivalent Fe sites. In the first Fe site, Fe(1) is bonded in a 5-coordinate geometry to one O(1), one O(4), one O(5), one O(6), and one F(4) atom. In the second Fe site, Fe(2) is bonded to one O(1), one O(2), one O(4), one F(3), one F(4), and one F(6) atom to form FeO3F3 octahedra that share corners with three equivalent Fe(5)O3F3 octahedra,  an edgeedge with one Mg(1)O3F3 octahedra,  an edgeedge with one Fe(3)O2F4 octahedra, and  an edgeedge with one Fe(6)O2F4 octahedra. The corner-sharing octahedral tilt angles range from 47-59°. In the third Fe site, Fe(3) is bonded to one O(2), one O(3), one F(1), one F(2), one F(4), and one F(5) atom to form FeO2F4 octahedra that share corners with three equivalent Fe(5)O3F3 octahedra,  an edgeedge with one Mg(1)O3F3 octahedra,  an edgeedge with one Fe(6)O2F4 octahedra, and  an edgeedge with one Fe(2)O3F3 octahedra. The corner-sharing octahedral tilt angles range from 47-63°. In the fourth Fe site, Fe(4) is bonded in a 5-coordinate geometry to one O(2), one O(3), one O(5), one O(6), and one F(1) atom. In the fifth Fe site, Fe(5) is bonded to one O(1), one O(3), one O(4), one F(1), one F(2), and one F(6) atom to form distorted FeO3F3 octahedra that share corners with two equivalent Mg(1)O3F3 octahedra, corners with two equivalent Fe(6)O2F4 octahedra, corners with three equivalent Fe(3)O2F4 octahedra, and corners with three equivalent Fe(2)O3F3 octahedra. The corner-sharing octahedral tilt angles range from 40-63°. In the sixth Fe site, Fe(6) is bonded to one O(5), one O(6), one F(2), one F(3), one F(5), and one F(6) atom to form FeO2F4 octahedra that share corners with two equivalent Fe(5)O3F3 octahedra,  an edgeedge with one Fe(3)O2F4 octahedra,  an edgeedge with one Fe(2)O3F3 octahedra, and edges with two equivalent Mg(1)O3F3 octahedra. The corner-sharing octahedral tilt angles range from 40-49°. There are six 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 trigonal planar geometry to one Fe(2), one Fe(3), and one Fe(4) atom. In the third O site, O(3) is bonded in a trigonal planar geometry to one Fe(3), one Fe(4), and one Fe(5) atom. In the fourth O site, O(4) is bonded to one Mg(1), one Fe(1), one Fe(2), and one Fe(5) atom to form distorted OMgFe3 trigonal pyramids that share corners with two equivalent O(6)MgFe3 trigonal pyramids, corners with two equivalent F(1)MgFe3 trigonal pyramids, and  an edgeedge with one O(5)MgFe3 trigonal pyramid. In the fifth O site, O(5) is bonded to one Mg(1), one Fe(1), one Fe(4), and one Fe(6) atom to form OMgFe3 trigonal pyramids that share corners with two equivalent O(6)MgFe3 trigonal pyramids, corners with two equivalent F(1)MgFe3 trigonal pyramids,  an edgeedge with one O(4)MgFe3 trigonal pyramid, and  an edgeedge with one O(6)MgFe3 trigonal pyramid. In the sixth O site, O(6) is bonded to one Mg(1), one Fe(1), one Fe(4), and one Fe(6) atom to form OMgFe3 trigonal pyramids that share corners with two equivalent O(4)MgFe3 trigonal pyramids, corners with two equivalent O(5)MgFe3 trigonal pyramids,  an edgeedge with one O(5)MgFe3 trigonal pyramid, and  an edgeedge with one F(1)MgFe3 trigonal pyramid. There are six inequivalent F sites. In the first F site, F(1) is bonded to one Mg(1), one Fe(3), one Fe(4), and one Fe(5) atom to form distorted FMgFe3 trigonal pyramids that share corners with two equivalent O(4)MgFe3 trigonal pyramids, corners with two equivalent O(5)MgFe3 trigonal pyramids, and  an edgeedge with one O(6)MgFe3 trigonal pyramid. In the second F site, F(2) is bonded in a distorted T-shaped geometry to one Fe(3), one Fe(5), and one Fe(6) atom. In the third F site, F(3) is bonded in a distorted T-shaped geometry to one Mg(1), one Fe(2), and one Fe(6) atom. In the fourth F site, F(4) is bonded in a distorted T-shaped geometry to one Fe(1), one Fe(2), and one Fe(3) atom. In the fifth F site, F(5) is bonded in a 3-coordinate geometry to one Mg(1), one Fe(3), and one Fe(6) atom. In the sixth F site, F(6) is bonded in a 3-coordinate geometry to one Fe(2), one Fe(5), and one Fe(6) atom.
MgFe6(OF)6 crystallizes in the triclinic P1 space group. Mg(1) is bonded to one O(4), one O(5), one O(6), one F(1), one F(3), and one F(5) atom to form MgO3F3 octahedra that share corners with two equivalent Fe(5)O3F3 octahedra,  an edgeedge with one Fe(3)O2F4 octahedra,  an edgeedge with one Fe(2)O3F3 octahedra, and edges with two equivalent Fe(6)O2F4 octahedra. The corner-sharing octahedral tilt angles range from 49-55°. The Mg(1)-O(4) bond length is 2.14 Å. The Mg(1)-O(5) bond length is 2.07 Å. The Mg(1)-O(6) bond length is 2.05 Å. The Mg(1)-F(1) bond length is 2.13 Å. The Mg(1)-F(3) bond length is 1.97 Å. The Mg(1)-F(5) bond length is 1.97 Å. There are six inequivalent Fe sites. In the first Fe site, Fe(1) is bonded in a 5-coordinate geometry to one O(1), one O(4), one O(5), one O(6), and one F(4) atom. The Fe(1)-O(1) bond length is 1.96 Å. The Fe(1)-O(4) bond length is 2.10 Å. The Fe(1)-O(5) bond length is 2.03 Å. The Fe(1)-O(6) bond length is 1.99 Å. The Fe(1)-F(4) bond length is 1.97 Å. In the second Fe site, Fe(2) is bonded to one O(1), one O(2), one O(4), one F(3), one F(4), and one F(6) atom to form FeO3F3 octahedra that share corners with three equivalent Fe(5)O3F3 octahedra,  an edgeedge with one Mg(1)O3F3 octahedra,  an edgeedge with one Fe(3)O2F4 octahedra, and  an edgeedge with one Fe(6)O2F4 octahedra. The corner-sharing octahedral tilt angles range from 47-59°. The Fe(2)-O(1) bond length is 1.98 Å. The Fe(2)-O(2) bond length is 1.88 Å. The Fe(2)-O(4) bond length is 2.10 Å. The Fe(2)-F(3) bond length is 2.10 Å. The Fe(2)-F(4) bond length is 2.20 Å. The Fe(2)-F(6) bond length is 2.01 Å. In the third Fe site, Fe(3) is bonded to one O(2), one O(3), one F(1), one F(2), one F(4), and one F(5) atom to form FeO2F4 octahedra that share corners with three equivalent Fe(5)O3F3 octahedra,  an edgeedge with one Mg(1)O3F3 octahedra,  an edgeedge with one Fe(6)O2F4 octahedra, and  an edgeedge with one Fe(2)O3F3 octahedra. The corner-sharing octahedral tilt angles range from 47-63°. The Fe(3)-O(2) bond length is 2.06 Å. The Fe(3)-O(3) bond length is 1.99 Å. The Fe(3)-F(1) bond length is 2.17 Å. The Fe(3)-F(2) bond length is 2.20 Å. The Fe(3)-F(4) bond length is 2.16 Å. The Fe(3)-F(5) bond length is 2.17 Å. In the fourth Fe site, Fe(4) is bonded in a 5-coordinate geometry to one O(2), one O(3), one O(5), one O(6), and one F(1) atom. The Fe(4)-O(2) bond length is 1.87 Å. The Fe(4)-O(3) bond length is 1.92 Å. The Fe(4)-O(5) bond length is 1.97 Å. The Fe(4)-O(6) bond length is 2.03 Å. The Fe(4)-F(1) bond length is 2.31 Å. In the fifth Fe site, Fe(5) is bonded to one O(1), one O(3), one O(4), one F(1), one F(2), and one F(6) atom to form distorted FeO3F3 octahedra that share corners with two equivalent Mg(1)O3F3 octahedra, corners with two equivalent Fe(6)O2F4 octahedra, corners with three equivalent Fe(3)O2F4 octahedra, and corners with three equivalent Fe(2)O3F3 octahedra. The corner-sharing octahedral tilt angles range from 40-63°. The Fe(5)-O(1) bond length is 1.97 Å. The Fe(5)-O(3) bond length is 1.93 Å. The Fe(5)-O(4) bond length is 1.97 Å. The Fe(5)-F(1) bond length is 2.40 Å. The Fe(5)-F(2) bond length is 2.06 Å. The Fe(5)-F(6) bond length is 2.35 Å. In the sixth Fe site, Fe(6) is bonded to one O(5), one O(6), one F(2), one F(3), one F(5), and one F(6) atom to form FeO2F4 octahedra that share corners with two equivalent Fe(5)O3F3 octahedra,  an edgeedge with one Fe(3)O2F4 octahedra,  an edgeedge with one Fe(2)O3F3 octahedra, and edges with two equivalent Mg(1)O3F3 octahedra. The corner-sharing octahedral tilt angles range from 40-49°. The Fe(6)-O(5) bond length is 2.08 Å. The Fe(6)-O(6) bond length is 2.09 Å. The Fe(6)-F(2) bond length is 2.21 Å. The Fe(6)-F(3) bond length is 2.12 Å. The Fe(6)-F(5) bond length is 2.11 Å. The Fe(6)-F(6) bond length is 2.20 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(1), one Fe(2), and one Fe(5) atom. In the second O site, O(2) is bonded in a trigonal planar geometry to one Fe(2), one Fe(3), and one Fe(4) atom. In the third O site, O(3) is bonded in a trigonal planar geometry to one Fe(3), one Fe(4), and one Fe(5) atom. In the fourth O site, O(4) is bonded to one Mg(1), one Fe(1), one Fe(2), and one Fe(5) atom to form distorted OMgFe3 trigonal pyramids that share corners with two equivalent O(6)MgFe3 trigonal pyramids, corners with two equivalent F(1)MgFe3 trigonal pyramids, and  an edgeedge with one O(5)MgFe3 trigonal pyramid. In the fifth O site, O(5) is bonded to one Mg(1), one Fe(1), one Fe(4), and one Fe(6) atom to form OMgFe3 trigonal pyramids that share corners with two equivalent O(6)MgFe3 trigonal pyramids, corners with two equivalent F(1)MgFe3 trigonal pyramids,  an edgeedge with one O(4)MgFe3 trigonal pyramid, and  an edgeedge with one O(6)MgFe3 trigonal pyramid. In the sixth O site, O(6) is bonded to one Mg(1), one Fe(1), one Fe(4), and one Fe(6) atom to form OMgFe3 trigonal pyramids that share corners with two equivalent O(4)MgFe3 trigonal pyramids, corners with two equivalent O(5)MgFe3 trigonal pyramids,  an edgeedge with one O(5)MgFe3 trigonal pyramid, and  an edgeedge with one F(1)MgFe3 trigonal pyramid. There are six inequivalent F sites. In the first F site, F(1) is bonded to one Mg(1), one Fe(3), one Fe(4), and one Fe(5) atom to form distorted FMgFe3 trigonal pyramids that share corners with two equivalent O(4)MgFe3 trigonal pyramids, corners with two equivalent O(5)MgFe3 trigonal pyramids, and  an edgeedge with one O(6)MgFe3 trigonal pyramid. In the second F site, F(2) is bonded in a distorted T-shaped geometry to one Fe(3), one Fe(5), and one Fe(6) atom. In the third F site, F(3) is bonded in a distorted T-shaped geometry to one Mg(1), one Fe(2), and one Fe(6) atom. In the fourth F site, F(4) is bonded in a distorted T-shaped geometry to one Fe(1), one Fe(2), and one Fe(3) atom. In the fifth F site, F(5) is bonded in a 3-coordinate geometry to one Mg(1), one Fe(3), and one Fe(6) atom. In the sixth F site, F(6) is bonded in a 3-coordinate geometry to one Fe(2), one Fe(5), and one Fe(6) atom.