MgMn4(OF)4 crystallizes in the triclinic P1 space group. Mg(1) is bonded to one O(1), one O(2), one O(4), one F(1), and one F(3) atom to form MgO3F2 trigonal bipyramids that share corners with three equivalent Mn(4)O3F2 trigonal bipyramids, edges with two equivalent Mn(3)O3F3 octahedra, and edges with two equivalent Mn(1)O2F4 pentagonal pyramids. There are four inequivalent Mn sites. In the first Mn site, Mn(1) is bonded to one O(2), one O(4), one F(1), one F(2), one F(3), and one F(4) atom to form distorted MnO2F4 pentagonal pyramids that share corners with two equivalent Mn(3)O3F3 octahedra,  an edgeedge with one Mn(3)O3F3 octahedra, edges with two equivalent Mg(1)O3F2 trigonal bipyramids, and edges with two equivalent Mn(4)O3F2 trigonal bipyramids. The corner-sharing octahedral tilt angles range from 27-45°. In the second Mn site, Mn(2) is bonded in a 6-coordinate geometry to one O(1), one O(2), one O(3), one F(2), one F(3), and one F(4) atom. In the third Mn site, Mn(3) is bonded to one O(1), one O(3), one O(4), one F(1), one F(2), and one F(3) atom to form MnO3F3 octahedra that share corners with two equivalent Mn(1)O2F4 pentagonal pyramids,  a cornercorner with one Mn(4)O3F2 trigonal bipyramid,  an edgeedge with one Mn(1)O2F4 pentagonal pyramid,  an edgeedge with one Mn(4)O3F2 trigonal bipyramid, and edges with two equivalent Mg(1)O3F2 trigonal bipyramids. In the fourth Mn site, Mn(4) is bonded to one O(2), one O(3), one O(4), one F(1), and one F(4) atom to form distorted MnO3F2 trigonal bipyramids that share  a cornercorner with one Mn(3)O3F3 octahedra, corners with three equivalent Mg(1)O3F2 trigonal bipyramids,  an edgeedge with one Mn(3)O3F3 octahedra, and edges with two equivalent Mn(1)O2F4 pentagonal pyramids. The corner-sharing octahedral tilt angles are 66°. There are four inequivalent O sites. In the first O site, O(1) is bonded in a T-shaped geometry to one Mg(1), one Mn(2), and one Mn(3) atom. In the second O site, O(2) is bonded to one Mg(1), one Mn(1), one Mn(2), and one Mn(4) atom to form corner-sharing OMgMn3 tetrahedra. In the third O site, O(3) is bonded in a trigonal planar geometry to one Mn(2), one Mn(3), and one Mn(4) atom. In the fourth O site, O(4) is bonded to one Mg(1), one Mn(1), one Mn(3), and one Mn(4) atom to form distorted corner-sharing OMgMn3 trigonal pyramids. There are four inequivalent F sites. In the first F site, F(1) is bonded in a rectangular see-saw-like geometry to one Mg(1), one Mn(1), one Mn(3), and one Mn(4) atom. In the second F site, F(2) is bonded in a 3-coordinate geometry to one Mn(1), one Mn(2), and one Mn(3) atom. In the third F site, F(3) is bonded in a distorted rectangular see-saw-like geometry to one Mg(1), one Mn(1), one Mn(2), and one Mn(3) atom. In the fourth F site, F(4) is bonded in a T-shaped geometry to one Mn(1), one Mn(2), and one Mn(4) atom.
MgMn4(OF)4 crystallizes in the triclinic P1 space group. Mg(1) is bonded to one O(1), one O(2), one O(4), one F(1), and one F(3) atom to form MgO3F2 trigonal bipyramids that share corners with three equivalent Mn(4)O3F2 trigonal bipyramids, edges with two equivalent Mn(3)O3F3 octahedra, and edges with two equivalent Mn(1)O2F4 pentagonal pyramids. The Mg(1)-O(1) bond length is 2.02 Å. The Mg(1)-O(2) bond length is 2.02 Å. The Mg(1)-O(4) bond length is 2.09 Å. The Mg(1)-F(1) bond length is 1.98 Å. The Mg(1)-F(3) bond length is 2.04 Å. There are four inequivalent Mn sites. In the first Mn site, Mn(1) is bonded to one O(2), one O(4), one F(1), one F(2), one F(3), and one F(4) atom to form distorted MnO2F4 pentagonal pyramids that share corners with two equivalent Mn(3)O3F3 octahedra,  an edgeedge with one Mn(3)O3F3 octahedra, edges with two equivalent Mg(1)O3F2 trigonal bipyramids, and edges with two equivalent Mn(4)O3F2 trigonal bipyramids. The corner-sharing octahedral tilt angles range from 27-45°. The Mn(1)-O(2) bond length is 2.19 Å. The Mn(1)-O(4) bond length is 2.05 Å. The Mn(1)-F(1) bond length is 2.24 Å. The Mn(1)-F(2) bond length is 2.22 Å. The Mn(1)-F(3) bond length is 2.06 Å. The Mn(1)-F(4) bond length is 2.31 Å. In the second Mn site, Mn(2) is bonded in a 6-coordinate geometry to one O(1), one O(2), one O(3), one F(2), one F(3), and one F(4) atom. The Mn(2)-O(1) bond length is 1.87 Å. The Mn(2)-O(2) bond length is 1.97 Å. The Mn(2)-O(3) bond length is 2.00 Å. The Mn(2)-F(2) bond length is 2.51 Å. The Mn(2)-F(3) bond length is 2.39 Å. The Mn(2)-F(4) bond length is 2.00 Å. In the third Mn site, Mn(3) is bonded to one O(1), one O(3), one O(4), one F(1), one F(2), and one F(3) atom to form MnO3F3 octahedra that share corners with two equivalent Mn(1)O2F4 pentagonal pyramids,  a cornercorner with one Mn(4)O3F2 trigonal bipyramid,  an edgeedge with one Mn(1)O2F4 pentagonal pyramid,  an edgeedge with one Mn(4)O3F2 trigonal bipyramid, and edges with two equivalent Mg(1)O3F2 trigonal bipyramids. The Mn(3)-O(1) bond length is 1.98 Å. The Mn(3)-O(3) bond length is 1.90 Å. The Mn(3)-O(4) bond length is 2.01 Å. The Mn(3)-F(1) bond length is 2.17 Å. The Mn(3)-F(2) bond length is 2.13 Å. The Mn(3)-F(3) bond length is 2.19 Å. In the fourth Mn site, Mn(4) is bonded to one O(2), one O(3), one O(4), one F(1), and one F(4) atom to form distorted MnO3F2 trigonal bipyramids that share  a cornercorner with one Mn(3)O3F3 octahedra, corners with three equivalent Mg(1)O3F2 trigonal bipyramids,  an edgeedge with one Mn(3)O3F3 octahedra, and edges with two equivalent Mn(1)O2F4 pentagonal pyramids. The corner-sharing octahedral tilt angles are 66°. The Mn(4)-O(2) bond length is 2.14 Å. The Mn(4)-O(3) bond length is 2.04 Å. The Mn(4)-O(4) bond length is 2.15 Å. The Mn(4)-F(1) bond length is 2.24 Å. The Mn(4)-F(4) bond length is 2.10 Å. There are four inequivalent O sites. In the first O site, O(1) is bonded in a T-shaped geometry to one Mg(1), one Mn(2), and one Mn(3) atom. In the second O site, O(2) is bonded to one Mg(1), one Mn(1), one Mn(2), and one Mn(4) atom to form corner-sharing OMgMn3 tetrahedra. In the third O site, O(3) is bonded in a trigonal planar geometry to one Mn(2), one Mn(3), and one Mn(4) atom. In the fourth O site, O(4) is bonded to one Mg(1), one Mn(1), one Mn(3), and one Mn(4) atom to form distorted corner-sharing OMgMn3 trigonal pyramids. There are four inequivalent F sites. In the first F site, F(1) is bonded in a rectangular see-saw-like geometry to one Mg(1), one Mn(1), one Mn(3), and one Mn(4) atom. In the second F site, F(2) is bonded in a 3-coordinate geometry to one Mn(1), one Mn(2), and one Mn(3) atom. In the third F site, F(3) is bonded in a distorted rectangular see-saw-like geometry to one Mg(1), one Mn(1), one Mn(2), and one Mn(3) atom. In the fourth F site, F(4) is bonded in a T-shaped geometry to one Mn(1), one Mn(2), and one Mn(4) atom.