MgCo6(O2F)4 crystallizes in the monoclinic Cm space group. Mg(1) is bonded in a 4-coordinate geometry to one O(1), two equivalent O(2), and one F(1) atom. There are six inequivalent Co sites. In the first Co site, Co(1) is bonded to one O(5), two equivalent O(3), one F(1), one F(2), and one F(3) atom to form CoO3F3 octahedra that share corners with three equivalent Co(5)O4F square pyramids,  an edgeedge with one Co(3)O3F3 octahedra, and  an edgeedge with one Co(2)O4F2 octahedra. In the second Co site, Co(2) is bonded to one O(1), one O(5), two equivalent O(2), one F(1), and one F(4) atom to form CoO4F2 octahedra that share corners with three equivalent Co(6)O4F square pyramids,  an edgeedge with one Co(1)O3F3 octahedra, and  an edgeedge with one Co(3)O3F3 octahedra. In the third Co site, Co(3) is bonded to one O(1), two equivalent O(4), one F(2), one F(3), and one F(4) atom to form CoO3F3 octahedra that share corners with three equivalent Co(5)O4F square pyramids, corners with three equivalent Co(6)O4F square pyramids,  an edgeedge with one Co(1)O3F3 octahedra, and  an edgeedge with one Co(2)O4F2 octahedra. In the fourth Co site, Co(4) is bonded in a 5-coordinate geometry to one O(5), two equivalent O(2), and two equivalent O(3) atoms. In the fifth Co site, Co(5) is bonded to two equivalent O(3), two equivalent O(4), and one F(2) atom to form CoO4F square pyramids that share corners with three equivalent Co(1)O3F3 octahedra, corners with three equivalent Co(3)O3F3 octahedra, and  an edgeedge with one Co(6)O4F square pyramid. The corner-sharing octahedral tilt angles range from 42-52°. In the sixth Co site, Co(6) is bonded to two equivalent O(2), two equivalent O(4), and one F(4) atom to form distorted CoO4F square pyramids that share corners with three equivalent Co(3)O3F3 octahedra, corners with three equivalent Co(2)O4F2 octahedra, and  an edgeedge with one Co(5)O4F square pyramid. The corner-sharing octahedral tilt angles range from 40-54°. There are five inequivalent O sites. In the first O site, O(1) is bonded in a T-shaped geometry to one Mg(1), one Co(2), and one Co(3) atom. In the second O site, O(2) is bonded in a distorted rectangular see-saw-like geometry to one Mg(1), one Co(2), one Co(4), and one Co(6) atom. In the third O site, O(3) is bonded in a trigonal planar geometry to one Co(1), one Co(4), and one Co(5) atom. In the fourth O site, O(4) is bonded in a trigonal planar geometry to one Co(3), one Co(5), and one Co(6) atom. In the fifth O site, O(5) is bonded in a distorted trigonal planar geometry to one Co(1), one Co(2), and one Co(4) atom. There are four inequivalent F sites. In the first F site, F(3) is bonded in an L-shaped geometry to one Co(1) and one Co(3) atom. In the second F site, F(4) is bonded in a distorted T-shaped geometry to one Co(2), one Co(3), and one Co(6) atom. In the third F site, F(1) is bonded in a distorted T-shaped geometry to one Mg(1), one Co(1), and one Co(2) atom. In the fourth F site, F(2) is bonded in a distorted T-shaped geometry to one Co(1), one Co(3), and one Co(5) atom.
MgCo6(O2F)4 crystallizes in the monoclinic Cm space group. Mg(1) is bonded in a 4-coordinate geometry to one O(1), two equivalent O(2), and one F(1) atom. The Mg(1)-O(1) bond length is 1.93 Å. Both Mg(1)-O(2) bond lengths are 2.00 Å. The Mg(1)-F(1) bond length is 1.86 Å. There are six inequivalent Co sites. In the first Co site, Co(1) is bonded to one O(5), two equivalent O(3), one F(1), one F(2), and one F(3) atom to form CoO3F3 octahedra that share corners with three equivalent Co(5)O4F square pyramids,  an edgeedge with one Co(3)O3F3 octahedra, and  an edgeedge with one Co(2)O4F2 octahedra. The Co(1)-O(5) bond length is 2.07 Å. Both Co(1)-O(3) bond lengths are 1.88 Å. The Co(1)-F(1) bond length is 2.02 Å. The Co(1)-F(2) bond length is 2.13 Å. The Co(1)-F(3) bond length is 1.94 Å. In the second Co site, Co(2) is bonded to one O(1), one O(5), two equivalent O(2), one F(1), and one F(4) atom to form CoO4F2 octahedra that share corners with three equivalent Co(6)O4F square pyramids,  an edgeedge with one Co(1)O3F3 octahedra, and  an edgeedge with one Co(3)O3F3 octahedra. The Co(2)-O(1) bond length is 1.88 Å. The Co(2)-O(5) bond length is 1.90 Å. Both Co(2)-O(2) bond lengths are 1.91 Å. The Co(2)-F(1) bond length is 2.26 Å. The Co(2)-F(4) bond length is 2.03 Å. In the third Co site, Co(3) is bonded to one O(1), two equivalent O(4), one F(2), one F(3), and one F(4) atom to form CoO3F3 octahedra that share corners with three equivalent Co(5)O4F square pyramids, corners with three equivalent Co(6)O4F square pyramids,  an edgeedge with one Co(1)O3F3 octahedra, and  an edgeedge with one Co(2)O4F2 octahedra. The Co(3)-O(1) bond length is 1.86 Å. Both Co(3)-O(4) bond lengths are 1.90 Å. The Co(3)-F(2) bond length is 2.02 Å. The Co(3)-F(3) bond length is 2.01 Å. The Co(3)-F(4) bond length is 2.23 Å. In the fourth Co site, Co(4) is bonded in a 5-coordinate geometry to one O(5), two equivalent O(2), and two equivalent O(3) atoms. The Co(4)-O(5) bond length is 1.81 Å. Both Co(4)-O(2) bond lengths are 2.09 Å. Both Co(4)-O(3) bond lengths are 1.99 Å. In the fifth Co site, Co(5) is bonded to two equivalent O(3), two equivalent O(4), and one F(2) atom to form CoO4F square pyramids that share corners with three equivalent Co(1)O3F3 octahedra, corners with three equivalent Co(3)O3F3 octahedra, and  an edgeedge with one Co(6)O4F square pyramid. The corner-sharing octahedral tilt angles range from 42-52°. Both Co(5)-O(3) bond lengths are 1.87 Å. Both Co(5)-O(4) bond lengths are 1.91 Å. The Co(5)-F(2) bond length is 2.35 Å. In the sixth Co site, Co(6) is bonded to two equivalent O(2), two equivalent O(4), and one F(4) atom to form distorted CoO4F square pyramids that share corners with three equivalent Co(3)O3F3 octahedra, corners with three equivalent Co(2)O4F2 octahedra, and  an edgeedge with one Co(5)O4F square pyramid. The corner-sharing octahedral tilt angles range from 40-54°. Both Co(6)-O(2) bond lengths are 2.03 Å. Both Co(6)-O(4) bond lengths are 1.86 Å. The Co(6)-F(4) bond length is 2.04 Å. There are five inequivalent O sites. In the first O site, O(1) is bonded in a T-shaped geometry to one Mg(1), one Co(2), and one Co(3) atom. In the second O site, O(2) is bonded in a distorted rectangular see-saw-like geometry to one Mg(1), one Co(2), one Co(4), and one Co(6) atom. In the third O site, O(3) is bonded in a trigonal planar geometry to one Co(1), one Co(4), and one Co(5) atom. In the fourth O site, O(4) is bonded in a trigonal planar geometry to one Co(3), one Co(5), and one Co(6) atom. In the fifth O site, O(5) is bonded in a distorted trigonal planar geometry to one Co(1), one Co(2), and one Co(4) atom. There are four inequivalent F sites. In the first F site, F(3) is bonded in an L-shaped geometry to one Co(1) and one Co(3) atom. In the second F site, F(4) is bonded in a distorted T-shaped geometry to one Co(2), one Co(3), and one Co(6) atom. In the third F site, F(1) is bonded in a distorted T-shaped geometry to one Mg(1), one Co(1), and one Co(2) atom. In the fourth F site, F(2) is bonded in a distorted T-shaped geometry to one Co(1), one Co(3), and one Co(5) atom.