MgMn4(O3F)2 crystallizes in the monoclinic C2 space group. Mg(1) is bonded to two equivalent O(1), two equivalent O(3), and two equivalent F(1) atoms to form MgO4F2 octahedra that share corners with four equivalent Mn(3)O4F2 octahedra, edges with two equivalent Mn(2)O4F2 octahedra, and faces with two equivalent Mn(3)O4F2 octahedra. The corner-sharing octahedral tilt angles range from 47-50°. There are three inequivalent Mn sites. In the first Mn site, Mn(1) is bonded in a distorted square co-planar geometry to two equivalent O(2) and two equivalent O(3) atoms. In the second Mn site, Mn(2) is bonded to two equivalent O(2), two equivalent O(3), and two equivalent F(1) atoms to form distorted MnO4F2 octahedra that share corners with eight equivalent Mn(3)O4F2 octahedra and edges with two equivalent Mg(1)O4F2 octahedra. The corner-sharing octahedral tilt angles range from 35-52°. In the third Mn site, Mn(3) is bonded to one O(2), one O(3), two equivalent O(1), and two equivalent F(1) atoms to form distorted MnO4F2 octahedra that share corners with two equivalent Mg(1)O4F2 octahedra, corners with four equivalent Mn(2)O4F2 octahedra, edges with two equivalent Mn(3)O4F2 octahedra, and  a faceface with one Mg(1)O4F2 octahedra. The corner-sharing octahedral tilt angles range from 35-52°. There are three inequivalent O sites. In the first O site, O(1) is bonded in a 3-coordinate geometry to one Mg(1) and two equivalent Mn(3) atoms. In the second O site, O(2) is bonded in a trigonal planar geometry to one Mn(1), one Mn(2), and one Mn(3) atom. 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 edge and corner-sharing OMgMn3 trigonal pyramids. F(1) is bonded in a rectangular see-saw-like geometry to one Mg(1), one Mn(2), and two equivalent Mn(3) atoms.
MgMn4(O3F)2 crystallizes in the monoclinic C2 space group. Mg(1) is bonded to two equivalent O(1), two equivalent O(3), and two equivalent F(1) atoms to form MgO4F2 octahedra that share corners with four equivalent Mn(3)O4F2 octahedra, edges with two equivalent Mn(2)O4F2 octahedra, and faces with two equivalent Mn(3)O4F2 octahedra. The corner-sharing octahedral tilt angles range from 47-50°. Both Mg(1)-O(1) bond lengths are 2.04 Å. Both Mg(1)-O(3) bond lengths are 2.04 Å. Both Mg(1)-F(1) bond lengths are 2.08 Å. There are three inequivalent Mn sites. In the first Mn site, Mn(1) is bonded in a distorted square co-planar geometry to two equivalent O(2) and two equivalent O(3) atoms. Both Mn(1)-O(2) bond lengths are 1.91 Å. Both Mn(1)-O(3) bond lengths are 1.97 Å. In the second Mn site, Mn(2) is bonded to two equivalent O(2), two equivalent O(3), and two equivalent F(1) atoms to form distorted MnO4F2 octahedra that share corners with eight equivalent Mn(3)O4F2 octahedra and edges with two equivalent Mg(1)O4F2 octahedra. The corner-sharing octahedral tilt angles range from 35-52°. Both Mn(2)-O(2) bond lengths are 1.93 Å. Both Mn(2)-O(3) bond lengths are 1.98 Å. Both Mn(2)-F(1) bond lengths are 2.38 Å. In the third Mn site, Mn(3) is bonded to one O(2), one O(3), two equivalent O(1), and two equivalent F(1) atoms to form distorted MnO4F2 octahedra that share corners with two equivalent Mg(1)O4F2 octahedra, corners with four equivalent Mn(2)O4F2 octahedra, edges with two equivalent Mn(3)O4F2 octahedra, and  a faceface with one Mg(1)O4F2 octahedra. The corner-sharing octahedral tilt angles range from 35-52°. The Mn(3)-O(2) bond length is 1.94 Å. The Mn(3)-O(3) bond length is 2.10 Å. There is one shorter (1.90 Å) and one longer (1.97 Å) Mn(3)-O(1) bond length. There is one shorter (2.16 Å) and one longer (2.34 Å) Mn(3)-F(1) bond length. There are three inequivalent O sites. In the first O site, O(1) is bonded in a 3-coordinate geometry to one Mg(1) and two equivalent Mn(3) atoms. In the second O site, O(2) is bonded in a trigonal planar geometry to one Mn(1), one Mn(2), and one Mn(3) atom. 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 edge and corner-sharing OMgMn3 trigonal pyramids. F(1) is bonded in a rectangular see-saw-like geometry to one Mg(1), one Mn(2), and two equivalent Mn(3) atoms.