MgMn4(O3F)2 crystallizes in the monoclinic Cm space group. Mg(1) is bonded to one O(1), two equivalent O(2), two equivalent O(3), and one F(2) atom to form MgO5F octahedra that share corners with two equivalent Mn(1)O5 trigonal bipyramids, edges with four equivalent Mn(3)O4F2 octahedra, and  an edgeedge with one Mn(1)O5 trigonal bipyramid. There are three inequivalent Mn sites. In the first Mn site, Mn(1) is bonded to one O(4), two equivalent O(2), and two equivalent O(3) atoms to form distorted MnO5 trigonal bipyramids that share corners with two equivalent Mg(1)O5F octahedra, corners with six equivalent Mn(3)O4F2 octahedra, and  an edgeedge with one Mg(1)O5F octahedra. The corner-sharing octahedral tilt angles range from 50-58°. In the second Mn site, Mn(2) is bonded in a 5-coordinate geometry to two equivalent O(2), two equivalent O(3), and one F(1) atom. In the third Mn site, Mn(3) is bonded to one O(1), one O(2), one O(3), one O(4), one F(1), and one F(2) atom to form MnO4F2 octahedra that share corners with three equivalent Mn(1)O5 trigonal bipyramids, edges with two equivalent Mg(1)O5F octahedra, and edges with two equivalent Mn(3)O4F2 octahedra. There are four inequivalent O sites. In the first O site, O(1) is bonded in a trigonal non-coplanar geometry to one Mg(1) and two equivalent Mn(3) atoms. In the second O site, O(2) is bonded to one Mg(1), one Mn(1), one Mn(2), and one Mn(3) atom to form a mixture of corner and edge-sharing OMgMn3 trigonal pyramids. In the third O site, O(3) is bonded to one Mg(1), one Mn(1), one Mn(2), and one Mn(3) atom to form a mixture of corner and edge-sharing OMgMn3 trigonal pyramids. In the fourth O site, O(4) is bonded in a distorted trigonal planar geometry to one Mn(1) and two equivalent Mn(3) atoms. There are two inequivalent F sites. In the first F site, F(1) is bonded in a distorted T-shaped geometry to one Mn(2) and two equivalent Mn(3) atoms. In the second F site, F(2) is bonded in a 3-coordinate geometry to one Mg(1) and two equivalent Mn(3) atoms.
MgMn4(O3F)2 crystallizes in the monoclinic Cm space group. Mg(1) is bonded to one O(1), two equivalent O(2), two equivalent O(3), and one F(2) atom to form MgO5F octahedra that share corners with two equivalent Mn(1)O5 trigonal bipyramids, edges with four equivalent Mn(3)O4F2 octahedra, and  an edgeedge with one Mn(1)O5 trigonal bipyramid. The Mg(1)-O(1) bond length is 1.97 Å. Both Mg(1)-O(2) bond lengths are 2.14 Å. Both Mg(1)-O(3) bond lengths are 2.11 Å. The Mg(1)-F(2) bond length is 1.99 Å. There are three inequivalent Mn sites. In the first Mn site, Mn(1) is bonded to one O(4), two equivalent O(2), and two equivalent O(3) atoms to form distorted MnO5 trigonal bipyramids that share corners with two equivalent Mg(1)O5F octahedra, corners with six equivalent Mn(3)O4F2 octahedra, and  an edgeedge with one Mg(1)O5F octahedra. The corner-sharing octahedral tilt angles range from 50-58°. The Mn(1)-O(4) bond length is 2.14 Å. Both Mn(1)-O(2) bond lengths are 2.02 Å. Both Mn(1)-O(3) bond lengths are 2.01 Å. In the second Mn site, Mn(2) is bonded in a 5-coordinate geometry to two equivalent O(2), two equivalent O(3), and one F(1) atom. Both Mn(2)-O(2) bond lengths are 1.99 Å. Both Mn(2)-O(3) bond lengths are 1.98 Å. The Mn(2)-F(1) bond length is 2.13 Å. In the third Mn site, Mn(3) is bonded to one O(1), one O(2), one O(3), one O(4), one F(1), and one F(2) atom to form MnO4F2 octahedra that share corners with three equivalent Mn(1)O5 trigonal bipyramids, edges with two equivalent Mg(1)O5F octahedra, and edges with two equivalent Mn(3)O4F2 octahedra. The Mn(3)-O(1) bond length is 1.90 Å. The Mn(3)-O(2) bond length is 2.05 Å. The Mn(3)-O(3) bond length is 2.05 Å. The Mn(3)-O(4) bond length is 1.91 Å. The Mn(3)-F(1) bond length is 2.16 Å. The Mn(3)-F(2) bond length is 2.18 Å. There are four inequivalent O sites. In the first O site, O(1) is bonded in a trigonal non-coplanar geometry to one Mg(1) and two equivalent Mn(3) atoms. In the second O site, O(2) is bonded to one Mg(1), one Mn(1), one Mn(2), and one Mn(3) atom to form a mixture of corner and edge-sharing OMgMn3 trigonal pyramids. In the third O site, O(3) is bonded to one Mg(1), one Mn(1), one Mn(2), and one Mn(3) atom to form a mixture of corner and edge-sharing OMgMn3 trigonal pyramids. In the fourth O site, O(4) is bonded in a distorted trigonal planar geometry to one Mn(1) and two equivalent Mn(3) atoms. There are two inequivalent F sites. In the first F site, F(1) is bonded in a distorted T-shaped geometry to one Mn(2) and two equivalent Mn(3) atoms. In the second F site, F(2) is bonded in a 3-coordinate geometry to one Mg(1) and two equivalent Mn(3) atoms.