MgMn8(OF)8 crystallizes in the triclinic P1 space group. Mg(1) is bonded to one O(3), one O(6), one O(8), one F(1), one F(2), and one F(8) atom to form MgO3F3 octahedra that share corners with two equivalent Mn(2)O3F3 octahedra, corners with two equivalent Mn(4)O3F3 octahedra, edges with two equivalent Mn(6)O3F3 octahedra, and edges with two equivalent Mn(8)O3F3 octahedra. The corner-sharing octahedral tilt angles range from 28-54°. There are eight inequivalent Mn sites. In the first Mn site, Mn(1) is bonded in a 6-coordinate geometry to one O(3), one O(6), one O(8), one F(1), one F(2), and one F(8) atom. In the second Mn site, Mn(2) is bonded to one O(1), one O(4), one O(8), one F(1), one F(4), and one F(6) atom to form distorted MnO3F3 octahedra that share corners with two equivalent Mg(1)O3F3 octahedra, corners with four equivalent Mn(6)O3F3 octahedra, corners with four equivalent Mn(7)O3F3 octahedra, and  an edgeedge with one Mn(3)O3F3 octahedra. The corner-sharing octahedral tilt angles range from 38-58°. In the third Mn site, Mn(3) is bonded to one O(1), one O(2), one O(7), one F(3), one F(6), and one F(7) atom to form a mixture of corner and edge-sharing MnO3F3 octahedra. The corner-sharing octahedral tilt angles range from 44-55°. In the fourth Mn site, Mn(4) is bonded to one O(2), one O(3), one O(5), one F(5), one F(7), and one F(8) atom to form distorted MnO3F3 octahedra that share corners with two equivalent Mg(1)O3F3 octahedra, corners with four equivalent Mn(5)O3F3 octahedra, corners with four equivalent Mn(8)O3F3 octahedra, and  an edgeedge with one Mn(3)O3F3 octahedra. The corner-sharing octahedral tilt angles range from 28-72°. In the fifth Mn site, Mn(5) is bonded to one O(2), one O(5), one O(7), one F(3), one F(5), and one F(7) atom to form a mixture of corner and edge-sharing MnO3F3 octahedra. The corner-sharing octahedral tilt angles range from 44-57°. In the sixth Mn site, Mn(6) is bonded to one O(4), one O(6), one O(8), one F(1), one F(2), and one F(4) atom to form MnO3F3 octahedra that share corners with four equivalent Mn(2)O3F3 octahedra,  an edgeedge with one Mn(7)O3F3 octahedra,  an edgeedge with one Mn(8)O3F3 octahedra, and edges with two equivalent Mg(1)O3F3 octahedra. The corner-sharing octahedral tilt angles range from 40-58°. In the seventh Mn site, Mn(7) is bonded to one O(1), one O(4), one O(7), one F(3), one F(4), and one F(6) atom to form a mixture of corner and edge-sharing MnO3F3 octahedra. The corner-sharing octahedral tilt angles range from 44-55°. In the eighth Mn site, Mn(8) is bonded to one O(3), one O(5), one O(6), one F(2), one F(5), and one F(8) atom to form distorted MnO3F3 octahedra that share corners with four equivalent Mn(4)O3F3 octahedra,  an edgeedge with one Mn(5)O3F3 octahedra,  an edgeedge with one Mn(6)O3F3 octahedra, and edges with two equivalent Mg(1)O3F3 octahedra. The corner-sharing octahedral tilt angles range from 45-72°. There are eight inequivalent O sites. In the first O site, O(1) is bonded in a trigonal planar geometry to one Mn(2), one Mn(3), and one Mn(7) atom. In the second O site, O(2) is bonded in a trigonal planar geometry to one Mn(3), one Mn(4), and one Mn(5) atom. In the third O site, O(3) is bonded in a distorted rectangular see-saw-like geometry to one Mg(1), one Mn(1), one Mn(4), and one Mn(8) atom. In the fourth O site, O(4) is bonded in a trigonal planar geometry to one Mn(2), one Mn(6), and one Mn(7) atom. In the fifth O site, O(5) is bonded in a trigonal planar geometry to one Mn(4), one Mn(5), and one Mn(8) atom. In the sixth O site, O(6) is bonded in a trigonal pyramidal geometry to one Mg(1), one Mn(1), one Mn(6), and one Mn(8) atom. In the seventh O site, O(7) is bonded in a trigonal planar geometry to one Mn(3), one Mn(5), and one Mn(7) atom. In the eighth O site, O(8) is bonded in a distorted rectangular see-saw-like geometry to one Mg(1), one Mn(1), one Mn(2), and one Mn(6) atom. There are eight inequivalent F sites. In the first F site, F(1) is bonded in a 4-coordinate geometry to one Mg(1), one Mn(1), one Mn(2), and one Mn(6) atom. In the second F site, F(2) is bonded in a distorted rectangular see-saw-like geometry to one Mg(1), one Mn(1), one Mn(6), and one Mn(8) atom. In the third F site, F(3) is bonded in a distorted T-shaped geometry to one Mn(3), one Mn(5), and one Mn(7) atom. In the fourth F site, F(4) is bonded in a distorted T-shaped geometry to one Mn(2), one Mn(6), and one Mn(7) atom. In the fifth F site, F(5) is bonded in a distorted T-shaped geometry to one Mn(4), one Mn(5), and one Mn(8) atom. In the sixth F site, F(6) is bonded in a distorted T-shaped geometry to one Mn(2), one Mn(3), and one Mn(7) atom. In the seventh F site, F(7) is bonded in a distorted T-shaped geometry to one Mn(3), one Mn(4), and one Mn(5) atom. In the eighth F site, F(8) is bonded in a 4-coordinate geometry to one Mg(1), one Mn(1), one Mn(4), and one Mn(8) atom.
MgMn8(OF)8 crystallizes in the triclinic P1 space group. Mg(1) is bonded to one O(3), one O(6), one O(8), one F(1), one F(2), and one F(8) atom to form MgO3F3 octahedra that share corners with two equivalent Mn(2)O3F3 octahedra, corners with two equivalent Mn(4)O3F3 octahedra, edges with two equivalent Mn(6)O3F3 octahedra, and edges with two equivalent Mn(8)O3F3 octahedra. The corner-sharing octahedral tilt angles range from 28-54°. The Mg(1)-O(3) bond length is 2.04 Å. The Mg(1)-O(6) bond length is 1.97 Å. The Mg(1)-O(8) bond length is 2.12 Å. The Mg(1)-F(1) bond length is 2.05 Å. The Mg(1)-F(2) bond length is 1.90 Å. The Mg(1)-F(8) bond length is 2.11 Å. There are eight inequivalent Mn sites. In the first Mn site, Mn(1) is bonded in a 6-coordinate geometry to one O(3), one O(6), one O(8), one F(1), one F(2), and one F(8) atom. The Mn(1)-O(3) bond length is 2.10 Å. The Mn(1)-O(6) bond length is 2.00 Å. The Mn(1)-O(8) bond length is 2.06 Å. The Mn(1)-F(1) bond length is 2.31 Å. The Mn(1)-F(2) bond length is 2.37 Å. The Mn(1)-F(8) bond length is 2.08 Å. In the second Mn site, Mn(2) is bonded to one O(1), one O(4), one O(8), one F(1), one F(4), and one F(6) atom to form distorted MnO3F3 octahedra that share corners with two equivalent Mg(1)O3F3 octahedra, corners with four equivalent Mn(6)O3F3 octahedra, corners with four equivalent Mn(7)O3F3 octahedra, and  an edgeedge with one Mn(3)O3F3 octahedra. The corner-sharing octahedral tilt angles range from 38-58°. The Mn(2)-O(1) bond length is 1.92 Å. The Mn(2)-O(4) bond length is 1.99 Å. The Mn(2)-O(8) bond length is 2.03 Å. The Mn(2)-F(1) bond length is 2.43 Å. The Mn(2)-F(4) bond length is 2.12 Å. The Mn(2)-F(6) bond length is 2.21 Å. In the third Mn site, Mn(3) is bonded to one O(1), one O(2), one O(7), one F(3), one F(6), and one F(7) atom to form a mixture of corner and edge-sharing MnO3F3 octahedra. The corner-sharing octahedral tilt angles range from 44-55°. The Mn(3)-O(1) bond length is 2.05 Å. The Mn(3)-O(2) bond length is 1.88 Å. The Mn(3)-O(7) bond length is 2.03 Å. The Mn(3)-F(3) bond length is 2.13 Å. The Mn(3)-F(6) bond length is 2.05 Å. The Mn(3)-F(7) bond length is 2.25 Å. In the fourth Mn site, Mn(4) is bonded to one O(2), one O(3), one O(5), one F(5), one F(7), and one F(8) atom to form distorted MnO3F3 octahedra that share corners with two equivalent Mg(1)O3F3 octahedra, corners with four equivalent Mn(5)O3F3 octahedra, corners with four equivalent Mn(8)O3F3 octahedra, and  an edgeedge with one Mn(3)O3F3 octahedra. The corner-sharing octahedral tilt angles range from 28-72°. The Mn(4)-O(2) bond length is 2.04 Å. The Mn(4)-O(3) bond length is 2.19 Å. The Mn(4)-O(5) bond length is 2.09 Å. The Mn(4)-F(5) bond length is 2.20 Å. The Mn(4)-F(7) bond length is 2.24 Å. The Mn(4)-F(8) bond length is 2.37 Å. In the fifth Mn site, Mn(5) is bonded to one O(2), one O(5), one O(7), one F(3), one F(5), and one F(7) atom to form a mixture of corner and edge-sharing MnO3F3 octahedra. The corner-sharing octahedral tilt angles range from 44-57°. The Mn(5)-O(2) bond length is 2.00 Å. The Mn(5)-O(5) bond length is 1.96 Å. The Mn(5)-O(7) bond length is 1.95 Å. The Mn(5)-F(3) bond length is 2.20 Å. The Mn(5)-F(5) bond length is 2.24 Å. The Mn(5)-F(7) bond length is 2.08 Å. In the sixth Mn site, Mn(6) is bonded to one O(4), one O(6), one O(8), one F(1), one F(2), and one F(4) atom to form MnO3F3 octahedra that share corners with four equivalent Mn(2)O3F3 octahedra,  an edgeedge with one Mn(7)O3F3 octahedra,  an edgeedge with one Mn(8)O3F3 octahedra, and edges with two equivalent Mg(1)O3F3 octahedra. The corner-sharing octahedral tilt angles range from 40-58°. The Mn(6)-O(4) bond length is 1.91 Å. The Mn(6)-O(6) bond length is 1.97 Å. The Mn(6)-O(8) bond length is 1.97 Å. The Mn(6)-F(1) bond length is 2.08 Å. The Mn(6)-F(2) bond length is 2.32 Å. The Mn(6)-F(4) bond length is 2.16 Å. In the seventh Mn site, Mn(7) is bonded to one O(1), one O(4), one O(7), one F(3), one F(4), and one F(6) atom to form a mixture of corner and edge-sharing MnO3F3 octahedra. The corner-sharing octahedral tilt angles range from 44-55°. The Mn(7)-O(1) bond length is 1.97 Å. The Mn(7)-O(4) bond length is 2.01 Å. The Mn(7)-O(7) bond length is 1.94 Å. The Mn(7)-F(3) bond length is 2.14 Å. The Mn(7)-F(4) bond length is 2.27 Å. The Mn(7)-F(6) bond length is 2.19 Å. In the eighth Mn site, Mn(8) is bonded to one O(3), one O(5), one O(6), one F(2), one F(5), and one F(8) atom to form distorted MnO3F3 octahedra that share corners with four equivalent Mn(4)O3F3 octahedra,  an edgeedge with one Mn(5)O3F3 octahedra,  an edgeedge with one Mn(6)O3F3 octahedra, and edges with two equivalent Mg(1)O3F3 octahedra. The corner-sharing octahedral tilt angles range from 45-72°. The Mn(8)-O(3) bond length is 1.95 Å. The Mn(8)-O(5) bond length is 1.90 Å. The Mn(8)-O(6) bond length is 2.04 Å. The Mn(8)-F(2) bond length is 2.40 Å. The Mn(8)-F(5) bond length is 2.08 Å. The Mn(8)-F(8) bond length is 2.15 Å. There are eight inequivalent O sites. In the first O site, O(1) is bonded in a trigonal planar geometry to one Mn(2), one Mn(3), and one Mn(7) atom. In the second O site, O(2) is bonded in a trigonal planar geometry to one Mn(3), one Mn(4), and one Mn(5) atom. In the third O site, O(3) is bonded in a distorted rectangular see-saw-like geometry to one Mg(1), one Mn(1), one Mn(4), and one Mn(8) atom. In the fourth O site, O(4) is bonded in a trigonal planar geometry to one Mn(2), one Mn(6), and one Mn(7) atom. In the fifth O site, O(5) is bonded in a trigonal planar geometry to one Mn(4), one Mn(5), and one Mn(8) atom. In the sixth O site, O(6) is bonded in a trigonal pyramidal geometry to one Mg(1), one Mn(1), one Mn(6), and one Mn(8) atom. In the seventh O site, O(7) is bonded in a trigonal planar geometry to one Mn(3), one Mn(5), and one Mn(7) atom. In the eighth O site, O(8) is bonded in a distorted rectangular see-saw-like geometry to one Mg(1), one Mn(1), one Mn(2), and one Mn(6) atom. There are eight inequivalent F sites. In the first F site, F(1) is bonded in a 4-coordinate geometry to one Mg(1), one Mn(1), one Mn(2), and one Mn(6) atom. In the second F site, F(2) is bonded in a distorted rectangular see-saw-like geometry to one Mg(1), one Mn(1), one Mn(6), and one Mn(8) atom. In the third F site, F(3) is bonded in a distorted T-shaped geometry to one Mn(3), one Mn(5), and one Mn(7) atom. In the fourth F site, F(4) is bonded in a distorted T-shaped geometry to one Mn(2), one Mn(6), and one Mn(7) atom. In the fifth F site, F(5) is bonded in a distorted T-shaped geometry to one Mn(4), one Mn(5), and one Mn(8) atom. In the sixth F site, F(6) is bonded in a distorted T-shaped geometry to one Mn(2), one Mn(3), and one Mn(7) atom. In the seventh F site, F(7) is bonded in a distorted T-shaped geometry to one Mn(3), one Mn(4), and one Mn(5) atom. In the eighth F site, F(8) is bonded in a 4-coordinate geometry to one Mg(1), one Mn(1), one Mn(4), and one Mn(8) atom.