MgMn8(OF)8 crystallizes in the triclinic P1 space group. Mg(1) is bonded to one O(3), one O(6), one F(2), and one F(8) atom to form distorted MgO2F2 trigonal pyramids that share corners with two equivalent Mn(4)O3F3 octahedra, corners with two equivalent Mn(6)O3F3 octahedra, and edges with two equivalent Mn(8)O3F3 octahedra. The corner-sharing octahedral tilt angles range from 53-71°. 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 a mixture of edge and corner-sharing MnO3F3 octahedra. The corner-sharing octahedral tilt angles range from 42-57°. 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 edge and corner-sharing MnO3F3 octahedra. The corner-sharing octahedral tilt angles range from 42-53°. 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 MnO3F3 octahedra that share corners with four equivalent Mn(5)O3F3 octahedra, corners with four equivalent Mn(8)O3F3 octahedra, corners with two equivalent Mg(1)O2F2 trigonal pyramids, and  an edgeedge with one Mn(3)O3F3 octahedra. The corner-sharing octahedral tilt angles range from 39-62°. 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 edge and corner-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, corners with two equivalent Mg(1)O2F2 trigonal pyramids,  an edgeedge with one Mn(7)O3F3 octahedra, and  an edgeedge with one Mn(8)O3F3 octahedra. The corner-sharing octahedral tilt angles range from 42-57°. 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 edge and corner-sharing MnO3F3 octahedra. The corner-sharing octahedral tilt angles range from 42-53°. 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)O2F2 trigonal pyramids. The corner-sharing octahedral tilt angles range from 39-62°. 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 to one Mg(1), one Mn(1), one Mn(4), and one Mn(8) atom to form a mixture of distorted edge and corner-sharing OMgMn3 trigonal pyramids. 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 to one Mg(1), one Mn(1), one Mn(6), and one Mn(8) atom to form a mixture of distorted edge and corner-sharing OMgMn3 tetrahedra. 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 trigonal planar geometry to 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 distorted T-shaped geometry to one Mn(1), one Mn(2), and one Mn(6) atom. In the second F site, F(2) is bonded in a 4-coordinate 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 3-coordinate 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 F(2), and one F(8) atom to form distorted MgO2F2 trigonal pyramids that share corners with two equivalent Mn(4)O3F3 octahedra, corners with two equivalent Mn(6)O3F3 octahedra, and edges with two equivalent Mn(8)O3F3 octahedra. The corner-sharing octahedral tilt angles range from 53-71°. The Mg(1)-O(3) bond length is 1.93 Å. The Mg(1)-O(6) bond length is 1.95 Å. The Mg(1)-F(2) bond length is 1.89 Å. The Mg(1)-F(8) bond length is 1.89 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 2.09 Å. The Mn(1)-O(6) bond length is 2.03 Å. The Mn(1)-O(8) bond length is 2.04 Å. The Mn(1)-F(1) bond length is 2.03 Å. The Mn(1)-F(2) bond length is 2.32 Å. The Mn(1)-F(8) bond length is 2.58 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 a mixture of edge and corner-sharing MnO3F3 octahedra. The corner-sharing octahedral tilt angles range from 42-57°. The Mn(2)-O(1) bond length is 1.93 Å. The Mn(2)-O(4) bond length is 2.01 Å. The Mn(2)-O(8) bond length is 2.01 Å. The Mn(2)-F(1) bond length is 2.25 Å. The Mn(2)-F(4) bond length is 2.16 Å. The Mn(2)-F(6) bond length is 2.18 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 edge and corner-sharing MnO3F3 octahedra. The corner-sharing octahedral tilt angles range from 42-53°. The Mn(3)-O(1) bond length is 2.00 Å. The Mn(3)-O(2) bond length is 1.89 Å. The Mn(3)-O(7) bond length is 2.07 Å. The Mn(3)-F(3) bond length is 2.18 Å. The Mn(3)-F(6) bond length is 2.04 Å. The Mn(3)-F(7) bond length is 2.22 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 MnO3F3 octahedra that share corners with four equivalent Mn(5)O3F3 octahedra, corners with four equivalent Mn(8)O3F3 octahedra, corners with two equivalent Mg(1)O2F2 trigonal pyramids, and  an edgeedge with one Mn(3)O3F3 octahedra. The corner-sharing octahedral tilt angles range from 39-62°. The Mn(4)-O(2) bond length is 2.03 Å. The Mn(4)-O(3) bond length is 2.12 Å. The Mn(4)-O(5) bond length is 2.07 Å. The Mn(4)-F(5) bond length is 2.18 Å. The Mn(4)-F(7) bond length is 2.18 Å. The Mn(4)-F(8) bond length is 2.33 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 edge and corner-sharing MnO3F3 octahedra. The corner-sharing octahedral tilt angles range from 44-57°. The Mn(5)-O(2) bond length is 1.99 Å. The Mn(5)-O(5) bond length is 2.01 Å. The Mn(5)-O(7) bond length is 1.93 Å. The Mn(5)-F(3) bond length is 2.15 Å. The Mn(5)-F(5) bond length is 2.33 Å. The Mn(5)-F(7) bond length is 2.11 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, corners with two equivalent Mg(1)O2F2 trigonal pyramids,  an edgeedge with one Mn(7)O3F3 octahedra, and  an edgeedge with one Mn(8)O3F3 octahedra. The corner-sharing octahedral tilt angles range from 42-57°. The Mn(6)-O(4) bond length is 1.96 Å. The Mn(6)-O(6) bond length is 2.09 Å. The Mn(6)-O(8) bond length is 1.96 Å. The Mn(6)-F(1) bond length is 2.09 Å. The Mn(6)-F(2) bond length is 2.28 Å. The Mn(6)-F(4) bond length is 2.17 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 edge and corner-sharing MnO3F3 octahedra. The corner-sharing octahedral tilt angles range from 42-53°. The Mn(7)-O(1) bond length is 1.98 Å. The Mn(7)-O(4) bond length is 1.99 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 2.23 Å. The Mn(7)-F(6) bond length is 2.20 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)O2F2 trigonal pyramids. The corner-sharing octahedral tilt angles range from 39-62°. The Mn(8)-O(3) bond length is 1.97 Å. The Mn(8)-O(5) bond length is 1.89 Å. The Mn(8)-O(6) bond length is 2.07 Å. The Mn(8)-F(2) bond length is 2.31 Å. The Mn(8)-F(5) bond length is 2.08 Å. The Mn(8)-F(8) bond length is 2.11 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 to one Mg(1), one Mn(1), one Mn(4), and one Mn(8) atom to form a mixture of distorted edge and corner-sharing OMgMn3 trigonal pyramids. 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 to one Mg(1), one Mn(1), one Mn(6), and one Mn(8) atom to form a mixture of distorted edge and corner-sharing OMgMn3 tetrahedra. 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 trigonal planar geometry to 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 distorted T-shaped geometry to one Mn(1), one Mn(2), and one Mn(6) atom. In the second F site, F(2) is bonded in a 4-coordinate 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 3-coordinate 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.