MgCo6(OF5)2 crystallizes in the triclinic P1 space group. Mg(1) is bonded to one O(1), one O(2), one F(1), one F(4), one F(7), and one F(8) atom to form MgO2F4 octahedra that share corners with two equivalent Co(5)OF5 octahedra, corners with two equivalent Co(6)OF5 octahedra, edges with two equivalent Co(1)OF5 octahedra, edges with two equivalent Co(2)OF5 octahedra, and faces with two equivalent Co(4)O2F4 octahedra. The corner-sharing octahedral tilt angles range from 39-47°. There are six inequivalent Co sites. In the first Co site, Co(1) is bonded to one O(2), one F(1), one F(2), one F(4), one F(8), and one F(9) atom to form CoOF5 octahedra that share corners with four equivalent Co(4)O2F4 octahedra, corners with four equivalent Co(5)OF5 octahedra,  an edgeedge with one Co(3)F6 octahedra,  an edgeedge with one Co(2)OF5 octahedra, and edges with two equivalent Mg(1)O2F4 octahedra. The corner-sharing octahedral tilt angles range from 42-66°. In the second Co site, Co(2) is bonded to one O(1), one F(1), one F(10), one F(3), one F(7), and one F(8) atom to form CoOF5 octahedra that share corners with four equivalent Co(4)O2F4 octahedra, corners with four equivalent Co(6)OF5 octahedra,  an edgeedge with one Co(3)F6 octahedra,  an edgeedge with one Co(1)OF5 octahedra, and edges with two equivalent Mg(1)O2F4 octahedra. The corner-sharing octahedral tilt angles range from 42-67°. In the third Co site, Co(3) is bonded to one F(10), one F(2), one F(3), one F(5), one F(6), and one F(9) atom to form a mixture of corner and edge-sharing CoF6 octahedra. The corner-sharing octahedral tilt angles range from 44-53°. In the fourth Co site, Co(4) is bonded to one O(1), one O(2), one F(1), one F(4), one F(7), and one F(8) atom to form CoO2F4 octahedra that share corners with four equivalent Co(1)OF5 octahedra, corners with four equivalent Co(2)OF5 octahedra,  an edgeedge with one Co(5)OF5 octahedra,  an edgeedge with one Co(6)OF5 octahedra, and faces with two equivalent Mg(1)O2F4 octahedra. The corner-sharing octahedral tilt angles range from 42-54°. In the fifth Co site, Co(5) is bonded to one O(2), one F(2), one F(4), one F(5), one F(6), and one F(9) atom to form CoOF5 octahedra that share corners with two equivalent Mg(1)O2F4 octahedra, corners with four equivalent Co(3)F6 octahedra, corners with four equivalent Co(1)OF5 octahedra,  an edgeedge with one Co(4)O2F4 octahedra, and  an edgeedge with one Co(6)OF5 octahedra. The corner-sharing octahedral tilt angles range from 40-66°. In the sixth Co site, Co(6) is bonded to one O(1), one F(10), one F(3), one F(5), one F(6), and one F(7) atom to form CoOF5 octahedra that share corners with two equivalent Mg(1)O2F4 octahedra, corners with four equivalent Co(3)F6 octahedra, corners with four equivalent Co(2)OF5 octahedra,  an edgeedge with one Co(4)O2F4 octahedra, and  an edgeedge with one Co(5)OF5 octahedra. The corner-sharing octahedral tilt angles range from 39-67°. There are two inequivalent O sites. In the first O site, O(1) 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 second O site, O(2) is bonded in a distorted rectangular see-saw-like geometry to one Mg(1), one Co(1), one Co(4), and one Co(5) atom. There are ten inequivalent F sites. In the first F site, F(1) is bonded to one Mg(1), one Co(1), one Co(2), and one Co(4) atom to form a mixture of distorted corner and edge-sharing FMgCo3 trigonal pyramids. In the second F site, F(2) is bonded in a distorted T-shaped geometry to one Co(1), one Co(3), and one Co(5) atom. In the third F site, F(3) is bonded in a distorted T-shaped geometry to one Co(2), one Co(3), and one Co(6) atom. In the fourth F site, F(4) is bonded in a rectangular see-saw-like geometry to one Mg(1), one Co(1), one Co(4), and one Co(5) atom. In the fifth F site, F(5) is bonded in a trigonal planar geometry to one Co(3), one Co(5), and one Co(6) atom. In the sixth F site, F(6) is bonded in a trigonal planar geometry to one Co(3), one Co(5), and one Co(6) atom. In the seventh F site, F(7) is bonded in a rectangular see-saw-like geometry to one Mg(1), one Co(2), one Co(4), and one Co(6) atom. In the eighth F site, F(8) is bonded to one Mg(1), one Co(1), one Co(2), and one Co(4) atom to form a mixture of distorted corner and edge-sharing FMgCo3 trigonal pyramids. In the ninth F site, F(9) is bonded in a distorted T-shaped geometry to one Co(1), one Co(3), and one Co(5) atom. In the tenth F site, F(10) is bonded in a distorted T-shaped geometry to one Co(2), one Co(3), and one Co(6) atom.
MgCo6(OF5)2 crystallizes in the triclinic P1 space group. Mg(1) is bonded to one O(1), one O(2), one F(1), one F(4), one F(7), and one F(8) atom to form MgO2F4 octahedra that share corners with two equivalent Co(5)OF5 octahedra, corners with two equivalent Co(6)OF5 octahedra, edges with two equivalent Co(1)OF5 octahedra, edges with two equivalent Co(2)OF5 octahedra, and faces with two equivalent Co(4)O2F4 octahedra. The corner-sharing octahedral tilt angles range from 39-47°. The Mg(1)-O(1) bond length is 2.07 Å. The Mg(1)-O(2) bond length is 2.06 Å. The Mg(1)-F(1) bond length is 1.95 Å. The Mg(1)-F(4) bond length is 2.06 Å. The Mg(1)-F(7) bond length is 2.06 Å. The Mg(1)-F(8) bond length is 1.95 Å. There are six inequivalent Co sites. In the first Co site, Co(1) is bonded to one O(2), one F(1), one F(2), one F(4), one F(8), and one F(9) atom to form CoOF5 octahedra that share corners with four equivalent Co(4)O2F4 octahedra, corners with four equivalent Co(5)OF5 octahedra,  an edgeedge with one Co(3)F6 octahedra,  an edgeedge with one Co(2)OF5 octahedra, and edges with two equivalent Mg(1)O2F4 octahedra. The corner-sharing octahedral tilt angles range from 42-66°. The Co(1)-O(2) bond length is 1.98 Å. The Co(1)-F(1) bond length is 2.17 Å. The Co(1)-F(2) bond length is 2.04 Å. The Co(1)-F(4) bond length is 2.20 Å. The Co(1)-F(8) bond length is 2.21 Å. The Co(1)-F(9) bond length is 2.02 Å. In the second Co site, Co(2) is bonded to one O(1), one F(1), one F(10), one F(3), one F(7), and one F(8) atom to form CoOF5 octahedra that share corners with four equivalent Co(4)O2F4 octahedra, corners with four equivalent Co(6)OF5 octahedra,  an edgeedge with one Co(3)F6 octahedra,  an edgeedge with one Co(1)OF5 octahedra, and edges with two equivalent Mg(1)O2F4 octahedra. The corner-sharing octahedral tilt angles range from 42-67°. The Co(2)-O(1) bond length is 1.98 Å. The Co(2)-F(1) bond length is 2.21 Å. The Co(2)-F(10) bond length is 2.05 Å. The Co(2)-F(3) bond length is 2.02 Å. The Co(2)-F(7) bond length is 2.19 Å. The Co(2)-F(8) bond length is 2.17 Å. In the third Co site, Co(3) is bonded to one F(10), one F(2), one F(3), one F(5), one F(6), and one F(9) atom to form a mixture of corner and edge-sharing CoF6 octahedra. The corner-sharing octahedral tilt angles range from 44-53°. The Co(3)-F(10) bond length is 2.08 Å. The Co(3)-F(2) bond length is 2.08 Å. The Co(3)-F(3) bond length is 2.08 Å. The Co(3)-F(5) bond length is 2.12 Å. The Co(3)-F(6) bond length is 2.11 Å. The Co(3)-F(9) bond length is 2.09 Å. In the fourth Co site, Co(4) is bonded to one O(1), one O(2), one F(1), one F(4), one F(7), and one F(8) atom to form CoO2F4 octahedra that share corners with four equivalent Co(1)OF5 octahedra, corners with four equivalent Co(2)OF5 octahedra,  an edgeedge with one Co(5)OF5 octahedra,  an edgeedge with one Co(6)OF5 octahedra, and faces with two equivalent Mg(1)O2F4 octahedra. The corner-sharing octahedral tilt angles range from 42-54°. The Co(4)-O(1) bond length is 1.95 Å. The Co(4)-O(2) bond length is 1.95 Å. The Co(4)-F(1) bond length is 2.21 Å. The Co(4)-F(4) bond length is 2.13 Å. The Co(4)-F(7) bond length is 2.12 Å. The Co(4)-F(8) bond length is 2.23 Å. In the fifth Co site, Co(5) is bonded to one O(2), one F(2), one F(4), one F(5), one F(6), and one F(9) atom to form CoOF5 octahedra that share corners with two equivalent Mg(1)O2F4 octahedra, corners with four equivalent Co(3)F6 octahedra, corners with four equivalent Co(1)OF5 octahedra,  an edgeedge with one Co(4)O2F4 octahedra, and  an edgeedge with one Co(6)OF5 octahedra. The corner-sharing octahedral tilt angles range from 40-66°. The Co(5)-O(2) bond length is 2.00 Å. The Co(5)-F(2) bond length is 2.18 Å. The Co(5)-F(4) bond length is 2.33 Å. The Co(5)-F(5) bond length is 2.08 Å. The Co(5)-F(6) bond length is 2.12 Å. The Co(5)-F(9) bond length is 2.17 Å. In the sixth Co site, Co(6) is bonded to one O(1), one F(10), one F(3), one F(5), one F(6), and one F(7) atom to form CoOF5 octahedra that share corners with two equivalent Mg(1)O2F4 octahedra, corners with four equivalent Co(3)F6 octahedra, corners with four equivalent Co(2)OF5 octahedra,  an edgeedge with one Co(4)O2F4 octahedra, and  an edgeedge with one Co(5)OF5 octahedra. The corner-sharing octahedral tilt angles range from 39-67°. The Co(6)-O(1) bond length is 2.00 Å. The Co(6)-F(10) bond length is 2.17 Å. The Co(6)-F(3) bond length is 2.17 Å. The Co(6)-F(5) bond length is 2.12 Å. The Co(6)-F(6) bond length is 2.08 Å. The Co(6)-F(7) bond length is 2.36 Å. There are two inequivalent O sites. In the first O site, O(1) 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 second O site, O(2) is bonded in a distorted rectangular see-saw-like geometry to one Mg(1), one Co(1), one Co(4), and one Co(5) atom. There are ten inequivalent F sites. In the first F site, F(1) is bonded to one Mg(1), one Co(1), one Co(2), and one Co(4) atom to form a mixture of distorted corner and edge-sharing FMgCo3 trigonal pyramids. In the second F site, F(2) is bonded in a distorted T-shaped geometry to one Co(1), one Co(3), and one Co(5) atom. In the third F site, F(3) is bonded in a distorted T-shaped geometry to one Co(2), one Co(3), and one Co(6) atom. In the fourth F site, F(4) is bonded in a rectangular see-saw-like geometry to one Mg(1), one Co(1), one Co(4), and one Co(5) atom. In the fifth F site, F(5) is bonded in a trigonal planar geometry to one Co(3), one Co(5), and one Co(6) atom. In the sixth F site, F(6) is bonded in a trigonal planar geometry to one Co(3), one Co(5), and one Co(6) atom. In the seventh F site, F(7) is bonded in a rectangular see-saw-like geometry to one Mg(1), one Co(2), one Co(4), and one Co(6) atom. In the eighth F site, F(8) is bonded to one Mg(1), one Co(1), one Co(2), and one Co(4) atom to form a mixture of distorted corner and edge-sharing FMgCo3 trigonal pyramids. In the ninth F site, F(9) is bonded in a distorted T-shaped geometry to one Co(1), one Co(3), and one Co(5) atom. In the tenth F site, F(10) is bonded in a distorted T-shaped geometry to one Co(2), one Co(3), and one Co(6) atom.