MgCo4OF11 crystallizes in the triclinic P1 space group. Mg(1) is bonded to one O(1), one F(10), one F(11), one F(5), one F(7), and one F(8) atom to form distorted MgOF5 pentagonal pyramids that share  a cornercorner with one Co(4)F6 octahedra, corners with two equivalent Co(1)OF5 octahedra,  an edgeedge with one Co(2)F6 octahedra, edges with two equivalent Co(3)OF5 octahedra, and  a faceface with one Co(4)F6 octahedra. The corner-sharing octahedral tilt angles range from 55-62°. There are four inequivalent Co sites. In the first Co site, Co(1) is bonded to one O(1), one F(10), one F(2), one F(3), one F(4), and one F(9) atom to form CoOF5 octahedra that share corners with two equivalent Co(3)OF5 octahedra, corners with four equivalent Co(2)F6 octahedra, and corners with two equivalent Mg(1)OF5 pentagonal pyramids. The corner-sharing octahedral tilt angles range from 31-41°. In the second Co site, Co(2) is bonded to one F(1), one F(10), one F(11), one F(2), one F(4), and one F(9) atom to form CoF6 octahedra that share corners with two equivalent Co(4)F6 octahedra, corners with four equivalent Co(1)OF5 octahedra, and  an edgeedge with one Mg(1)OF5 pentagonal pyramid. The corner-sharing octahedral tilt angles range from 34-48°. In the third Co site, Co(3) is bonded to one O(1), one F(3), one F(5), one F(6), one F(7), and one F(8) atom to form CoOF5 octahedra that share corners with two equivalent Co(1)OF5 octahedra, corners with four equivalent Co(4)F6 octahedra, and edges with two equivalent Mg(1)OF5 pentagonal pyramids. The corner-sharing octahedral tilt angles range from 31-47°. In the fourth Co site, Co(4) is bonded to one F(1), one F(11), one F(5), one F(6), one F(7), and one F(8) atom to form CoF6 octahedra that share corners with two equivalent Co(2)F6 octahedra, corners with four equivalent Co(3)OF5 octahedra,  a cornercorner with one Mg(1)OF5 pentagonal pyramid, and  a faceface with one Mg(1)OF5 pentagonal pyramid. The corner-sharing octahedral tilt angles range from 35-48°. O(1) is bonded in a distorted trigonal planar geometry to one Mg(1), one Co(1), and one Co(3) atom. There are eleven inequivalent F sites. In the first F site, F(1) is bonded in a bent 120 degrees geometry to one Co(2) and one Co(4) atom. In the second F site, F(2) is bonded in a bent 150 degrees geometry to one Co(1) and one Co(2) atom. In the third F site, F(3) is bonded in a bent 150 degrees geometry to one Co(1) and one Co(3) atom. In the fourth F site, F(4) is bonded in a bent 150 degrees geometry to one Co(1) and one Co(2) atom. In the fifth F site, F(5) is bonded in a distorted trigonal planar geometry to one Mg(1), one Co(3), and one Co(4) atom. In the sixth F site, F(6) is bonded in a bent 150 degrees geometry to one Co(3) and one Co(4) atom. In the seventh F site, F(7) is bonded in a T-shaped geometry to one Mg(1), one Co(3), and one Co(4) atom. In the eighth F site, F(8) is bonded in a T-shaped geometry to one Mg(1), one Co(3), and one Co(4) atom. In the ninth F site, F(9) is bonded in a bent 150 degrees geometry to one Co(1) and one Co(2) atom. In the tenth F site, F(10) is bonded in a distorted trigonal planar geometry to one Mg(1), one Co(1), and one Co(2) atom. In the eleventh F site, F(11) is bonded in a T-shaped geometry to one Mg(1), one Co(2), and one Co(4) atom.
MgCo4OF11 crystallizes in the triclinic P1 space group. Mg(1) is bonded to one O(1), one F(10), one F(11), one F(5), one F(7), and one F(8) atom to form distorted MgOF5 pentagonal pyramids that share  a cornercorner with one Co(4)F6 octahedra, corners with two equivalent Co(1)OF5 octahedra,  an edgeedge with one Co(2)F6 octahedra, edges with two equivalent Co(3)OF5 octahedra, and  a faceface with one Co(4)F6 octahedra. The corner-sharing octahedral tilt angles range from 55-62°. The Mg(1)-O(1) bond length is 2.03 Å. The Mg(1)-F(10) bond length is 1.97 Å. The Mg(1)-F(11) bond length is 2.08 Å. The Mg(1)-F(5) bond length is 2.00 Å. The Mg(1)-F(7) bond length is 2.13 Å. The Mg(1)-F(8) bond length is 2.09 Å. There are four inequivalent Co sites. In the first Co site, Co(1) is bonded to one O(1), one F(10), one F(2), one F(3), one F(4), and one F(9) atom to form CoOF5 octahedra that share corners with two equivalent Co(3)OF5 octahedra, corners with four equivalent Co(2)F6 octahedra, and corners with two equivalent Mg(1)OF5 pentagonal pyramids. The corner-sharing octahedral tilt angles range from 31-41°. The Co(1)-O(1) bond length is 1.80 Å. The Co(1)-F(10) bond length is 2.11 Å. The Co(1)-F(2) bond length is 2.01 Å. The Co(1)-F(3) bond length is 1.93 Å. The Co(1)-F(4) bond length is 2.15 Å. The Co(1)-F(9) bond length is 2.12 Å. In the second Co site, Co(2) is bonded to one F(1), one F(10), one F(11), one F(2), one F(4), and one F(9) atom to form CoF6 octahedra that share corners with two equivalent Co(4)F6 octahedra, corners with four equivalent Co(1)OF5 octahedra, and  an edgeedge with one Mg(1)OF5 pentagonal pyramid. The corner-sharing octahedral tilt angles range from 34-48°. The Co(2)-F(1) bond length is 1.95 Å. The Co(2)-F(10) bond length is 2.10 Å. The Co(2)-F(11) bond length is 2.04 Å. The Co(2)-F(2) bond length is 1.91 Å. The Co(2)-F(4) bond length is 1.85 Å. The Co(2)-F(9) bond length is 1.86 Å. In the third Co site, Co(3) is bonded to one O(1), one F(3), one F(5), one F(6), one F(7), and one F(8) atom to form CoOF5 octahedra that share corners with two equivalent Co(1)OF5 octahedra, corners with four equivalent Co(4)F6 octahedra, and edges with two equivalent Mg(1)OF5 pentagonal pyramids. The corner-sharing octahedral tilt angles range from 31-47°. The Co(3)-O(1) bond length is 2.00 Å. The Co(3)-F(3) bond length is 1.97 Å. The Co(3)-F(5) bond length is 2.10 Å. The Co(3)-F(6) bond length is 2.11 Å. The Co(3)-F(7) bond length is 2.16 Å. The Co(3)-F(8) bond length is 2.05 Å. In the fourth Co site, Co(4) is bonded to one F(1), one F(11), one F(5), one F(6), one F(7), and one F(8) atom to form CoF6 octahedra that share corners with two equivalent Co(2)F6 octahedra, corners with four equivalent Co(3)OF5 octahedra,  a cornercorner with one Mg(1)OF5 pentagonal pyramid, and  a faceface with one Mg(1)OF5 pentagonal pyramid. The corner-sharing octahedral tilt angles range from 35-48°. The Co(4)-F(1) bond length is 1.89 Å. The Co(4)-F(11) bond length is 2.03 Å. The Co(4)-F(5) bond length is 2.00 Å. The Co(4)-F(6) bond length is 1.81 Å. The Co(4)-F(7) bond length is 1.95 Å. The Co(4)-F(8) bond length is 2.01 Å. O(1) is bonded in a distorted trigonal planar geometry to one Mg(1), one Co(1), and one Co(3) atom. There are eleven inequivalent F sites. In the first F site, F(1) is bonded in a bent 120 degrees geometry to one Co(2) and one Co(4) atom. In the second F site, F(2) is bonded in a bent 150 degrees geometry to one Co(1) and one Co(2) atom. In the third F site, F(3) is bonded in a bent 150 degrees geometry to one Co(1) and one Co(3) atom. In the fourth F site, F(4) is bonded in a bent 150 degrees geometry to one Co(1) and one Co(2) atom. In the fifth F site, F(5) is bonded in a distorted trigonal planar geometry to one Mg(1), one Co(3), and one Co(4) atom. In the sixth F site, F(6) is bonded in a bent 150 degrees geometry to one Co(3) and one Co(4) atom. In the seventh F site, F(7) is bonded in a T-shaped geometry to one Mg(1), one Co(3), and one Co(4) atom. In the eighth F site, F(8) is bonded in a T-shaped geometry to one Mg(1), one Co(3), and one Co(4) atom. In the ninth F site, F(9) is bonded in a bent 150 degrees geometry to one Co(1) and one Co(2) atom. In the tenth F site, F(10) is bonded in a distorted trigonal planar geometry to one Mg(1), one Co(1), and one Co(2) atom. In the eleventh F site, F(11) is bonded in a T-shaped geometry to one Mg(1), one Co(2), and one Co(4) atom.