MgCo4(O3F)2 crystallizes in the triclinic P1 space group. Mg(1) is bonded in a distorted rectangular see-saw-like geometry to one O(3), one O(5), one O(6), and one F(2) atom. There are four inequivalent Co sites. In the first Co site, Co(1) is bonded to one O(1), one O(2), one O(4), one O(6), one F(1), and one F(2) atom to form CoO4F2 octahedra that share corners with three equivalent Co(3)O4F square pyramids and edges with two equivalent Co(2)O4F2 octahedra. In the second Co site, Co(2) is bonded to one O(1), one O(3), one O(5), one O(6), one F(1), and one F(2) atom to form CoO4F2 octahedra that share corners with three equivalent Co(3)O4F square pyramids and edges with two equivalent Co(1)O4F2 octahedra. In the third Co site, Co(3) is bonded to one O(2), one O(3), one O(4), one O(5), and one F(1) atom to form distorted corner-sharing CoO4F square pyramids. The corner-sharing octahedral tilt angles range from 39-53°. In the fourth Co site, Co(4) is bonded in a 5-coordinate geometry to one O(1), one O(2), one O(3), one O(4), and one O(5) atom. There are six inequivalent O sites. In the first O site, O(1) is bonded in a distorted trigonal planar geometry to one Co(1), one Co(2), and one Co(4) atom. In the second O site, O(2) is bonded in a distorted trigonal planar geometry to one Co(1), one Co(3), and one Co(4) atom. In the third O site, O(3) is bonded in a rectangular see-saw-like geometry to one Mg(1), one Co(2), one Co(3), and one Co(4) atom. In the fourth O site, O(4) is bonded in a distorted trigonal planar geometry to one Co(1), one Co(3), and one Co(4) atom. In the fifth O site, O(5) is bonded in a rectangular see-saw-like geometry to one Mg(1), one Co(2), one Co(3), and one Co(4) atom. In the sixth O site, O(6) is bonded in a T-shaped geometry to one Mg(1), one Co(1), and one Co(2) atom. There are two inequivalent F sites. In the first F site, F(1) is bonded in a 3-coordinate geometry to one Co(1), one Co(2), and one Co(3) atom. In the second F site, F(2) is bonded in a T-shaped geometry to one Mg(1), one Co(1), and one Co(2) atom.
MgCo4(O3F)2 crystallizes in the triclinic P1 space group. Mg(1) is bonded in a distorted rectangular see-saw-like geometry to one O(3), one O(5), one O(6), and one F(2) atom. The Mg(1)-O(3) bond length is 2.01 Å. The Mg(1)-O(5) bond length is 2.00 Å. The Mg(1)-O(6) bond length is 1.93 Å. The Mg(1)-F(2) bond length is 1.85 Å. There are four inequivalent Co sites. In the first Co site, Co(1) is bonded to one O(1), one O(2), one O(4), one O(6), one F(1), and one F(2) atom to form CoO4F2 octahedra that share corners with three equivalent Co(3)O4F square pyramids and edges with two equivalent Co(2)O4F2 octahedra. The Co(1)-O(1) bond length is 1.97 Å. The Co(1)-O(2) bond length is 1.89 Å. The Co(1)-O(4) bond length is 1.89 Å. The Co(1)-O(6) bond length is 1.85 Å. The Co(1)-F(1) bond length is 2.30 Å. The Co(1)-F(2) bond length is 2.11 Å. In the second Co site, Co(2) is bonded to one O(1), one O(3), one O(5), one O(6), one F(1), and one F(2) atom to form CoO4F2 octahedra that share corners with three equivalent Co(3)O4F square pyramids and edges with two equivalent Co(1)O4F2 octahedra. The Co(2)-O(1) bond length is 1.93 Å. The Co(2)-O(3) bond length is 1.90 Å. The Co(2)-O(5) bond length is 1.90 Å. The Co(2)-O(6) bond length is 1.86 Å. The Co(2)-F(1) bond length is 2.03 Å. The Co(2)-F(2) bond length is 2.20 Å. In the third Co site, Co(3) is bonded to one O(2), one O(3), one O(4), one O(5), and one F(1) atom to form distorted corner-sharing CoO4F square pyramids. The corner-sharing octahedral tilt angles range from 39-53°. The Co(3)-O(2) bond length is 1.85 Å. The Co(3)-O(3) bond length is 1.98 Å. The Co(3)-O(4) bond length is 1.85 Å. The Co(3)-O(5) bond length is 1.98 Å. The Co(3)-F(1) bond length is 2.04 Å. In the fourth Co site, Co(4) is bonded in a 5-coordinate geometry to one O(1), one O(2), one O(3), one O(4), and one O(5) atom. The Co(4)-O(1) bond length is 1.84 Å. The Co(4)-O(2) bond length is 1.98 Å. The Co(4)-O(3) bond length is 2.08 Å. The Co(4)-O(4) bond length is 1.98 Å. The Co(4)-O(5) bond length is 2.08 Å. There are six inequivalent O sites. In the first O site, O(1) is bonded in a distorted trigonal planar geometry to one Co(1), one Co(2), and one Co(4) atom. In the second O site, O(2) is bonded in a distorted trigonal planar geometry to one Co(1), one Co(3), and one Co(4) atom. In the third O site, O(3) is bonded in a rectangular see-saw-like geometry to one Mg(1), one Co(2), one Co(3), and one Co(4) atom. In the fourth O site, O(4) is bonded in a distorted trigonal planar geometry to one Co(1), one Co(3), and one Co(4) atom. In the fifth O site, O(5) is bonded in a rectangular see-saw-like geometry to one Mg(1), one Co(2), one Co(3), and one Co(4) atom. In the sixth O site, O(6) is bonded in a T-shaped geometry to one Mg(1), one Co(1), and one Co(2) atom. There are two inequivalent F sites. In the first F site, F(1) is bonded in a 3-coordinate geometry to one Co(1), one Co(2), and one Co(3) atom. In the second F site, F(2) is bonded in a T-shaped geometry to one Mg(1), one Co(1), and one Co(2) atom.