MgCu6(OF5)2 crystallizes in the triclinic P1 space group. Mg(1) is bonded to one O(1), one F(1), one F(10), one F(5), one F(6), and one F(9) atom to form MgOF5 octahedra that share corners with two equivalent Cu(1)OF5 octahedra,  a cornercorner with one Cu(5)OF4 square pyramid, edges with two equivalent Cu(4)OF5 octahedra, and  an edgeedge with one Cu(5)OF4 square pyramid. The corner-sharing octahedral tilt angles range from 46-59°. There are six inequivalent Cu sites. In the first Cu site, Cu(1) is bonded to one O(2), one F(1), one F(10), one F(2), one F(4), and one F(7) atom to form distorted CuOF5 octahedra that share corners with two equivalent Mg(1)OF5 octahedra, corners with two equivalent Cu(4)OF5 octahedra, corners with two equivalent Cu(5)OF4 square pyramids, and corners with three equivalent Cu(2)OF4 square pyramids. The corner-sharing octahedral tilt angles range from 42-59°. In the second Cu site, Cu(2) is bonded to one O(2), one F(3), one F(4), one F(7), and one F(8) atom to form distorted CuOF4 square pyramids that share corners with three equivalent Cu(1)OF5 octahedra,  an edgeedge with one Cu(4)OF5 octahedra, and  an edgeedge with one Cu(5)OF4 square pyramid. The corner-sharing octahedral tilt angles range from 48-56°. In the third Cu site, Cu(3) is bonded in a 5-coordinate geometry to one O(1), one F(1), one F(2), one F(3), and one F(6) atom. In the fourth Cu site, Cu(4) is bonded to one O(1), one F(10), one F(5), one F(7), one F(8), and one F(9) atom to form CuOF5 octahedra that share corners with two equivalent Cu(1)OF5 octahedra, edges with two equivalent Mg(1)OF5 octahedra,  an edgeedge with one Cu(2)OF4 square pyramid, and  an edgeedge with one Cu(5)OF4 square pyramid. The corner-sharing octahedral tilt angles range from 42-47°. In the fifth Cu site, Cu(5) is bonded to one O(1), one F(1), one F(3), one F(4), and one F(9) atom to form distorted CuOF4 square pyramids that share  a cornercorner with one Mg(1)OF5 octahedra, corners with two equivalent Cu(1)OF5 octahedra,  an edgeedge with one Mg(1)OF5 octahedra,  an edgeedge with one Cu(4)OF5 octahedra, and  an edgeedge with one Cu(2)OF4 square pyramid. The corner-sharing octahedral tilt angles range from 51-80°. In the sixth Cu site, Cu(6) is bonded in a 5-coordinate geometry to one O(2), one F(5), one F(6), one F(8), and one F(9) atom. There are two inequivalent O sites. In the first O site, O(1) is bonded in a trigonal pyramidal geometry to one Mg(1), one Cu(3), one Cu(4), and one Cu(5) atom. In the second O site, O(2) is bonded in a trigonal planar geometry to one Cu(1), one Cu(2), and one Cu(6) atom. There are ten inequivalent F sites. In the first F site, F(1) is bonded in a distorted rectangular see-saw-like geometry to one Mg(1), one Cu(1), one Cu(3), and one Cu(5) atom. In the second F site, F(2) is bonded in a bent 120 degrees geometry to one Cu(1) and one Cu(3) atom. In the third F site, F(3) is bonded in a distorted trigonal planar geometry to one Cu(2), one Cu(3), and one Cu(5) atom. In the fourth F site, F(4) is bonded in a distorted trigonal planar geometry to one Cu(1), one Cu(2), and one Cu(5) atom. In the fifth F site, F(5) is bonded in a trigonal non-coplanar geometry to one Mg(1), one Cu(4), and one Cu(6) atom. In the sixth F site, F(6) is bonded in a 3-coordinate geometry to one Mg(1), one Cu(3), and one Cu(6) atom. In the seventh F site, F(7) is bonded in a distorted trigonal planar geometry to one Cu(1), one Cu(2), and one Cu(4) atom. In the eighth F site, F(8) is bonded in a distorted trigonal planar geometry to one Cu(2), one Cu(4), and one Cu(6) atom. In the ninth F site, F(9) is bonded in a rectangular see-saw-like geometry to one Mg(1), one Cu(4), one Cu(5), and one Cu(6) atom. In the tenth F site, F(10) is bonded in a distorted L-shaped geometry to one Mg(1), one Cu(1), and one Cu(4) atom.
MgCu6(OF5)2 crystallizes in the triclinic P1 space group. Mg(1) is bonded to one O(1), one F(1), one F(10), one F(5), one F(6), and one F(9) atom to form MgOF5 octahedra that share corners with two equivalent Cu(1)OF5 octahedra,  a cornercorner with one Cu(5)OF4 square pyramid, edges with two equivalent Cu(4)OF5 octahedra, and  an edgeedge with one Cu(5)OF4 square pyramid. The corner-sharing octahedral tilt angles range from 46-59°. The Mg(1)-O(1) bond length is 2.05 Å. The Mg(1)-F(1) bond length is 1.96 Å. The Mg(1)-F(10) bond length is 1.98 Å. The Mg(1)-F(5) bond length is 2.06 Å. The Mg(1)-F(6) bond length is 2.02 Å. The Mg(1)-F(9) bond length is 1.99 Å. There are six inequivalent Cu sites. In the first Cu site, Cu(1) is bonded to one O(2), one F(1), one F(10), one F(2), one F(4), and one F(7) atom to form distorted CuOF5 octahedra that share corners with two equivalent Mg(1)OF5 octahedra, corners with two equivalent Cu(4)OF5 octahedra, corners with two equivalent Cu(5)OF4 square pyramids, and corners with three equivalent Cu(2)OF4 square pyramids. The corner-sharing octahedral tilt angles range from 42-59°. The Cu(1)-O(2) bond length is 1.83 Å. The Cu(1)-F(1) bond length is 2.40 Å. The Cu(1)-F(10) bond length is 2.52 Å. The Cu(1)-F(2) bond length is 1.94 Å. The Cu(1)-F(4) bond length is 1.94 Å. The Cu(1)-F(7) bond length is 1.93 Å. In the second Cu site, Cu(2) is bonded to one O(2), one F(3), one F(4), one F(7), and one F(8) atom to form distorted CuOF4 square pyramids that share corners with three equivalent Cu(1)OF5 octahedra,  an edgeedge with one Cu(4)OF5 octahedra, and  an edgeedge with one Cu(5)OF4 square pyramid. The corner-sharing octahedral tilt angles range from 48-56°. The Cu(2)-O(2) bond length is 1.88 Å. The Cu(2)-F(3) bond length is 1.99 Å. The Cu(2)-F(4) bond length is 2.19 Å. The Cu(2)-F(7) bond length is 2.21 Å. The Cu(2)-F(8) bond length is 1.95 Å. In the third Cu site, Cu(3) is bonded in a 5-coordinate geometry to one O(1), one F(1), one F(2), one F(3), and one F(6) atom. The Cu(3)-O(1) bond length is 1.94 Å. The Cu(3)-F(1) bond length is 2.45 Å. The Cu(3)-F(2) bond length is 1.92 Å. The Cu(3)-F(3) bond length is 2.15 Å. The Cu(3)-F(6) bond length is 1.95 Å. In the fourth Cu site, Cu(4) is bonded to one O(1), one F(10), one F(5), one F(7), one F(8), and one F(9) atom to form CuOF5 octahedra that share corners with two equivalent Cu(1)OF5 octahedra, edges with two equivalent Mg(1)OF5 octahedra,  an edgeedge with one Cu(2)OF4 square pyramid, and  an edgeedge with one Cu(5)OF4 square pyramid. The corner-sharing octahedral tilt angles range from 42-47°. The Cu(4)-O(1) bond length is 1.93 Å. The Cu(4)-F(10) bond length is 1.95 Å. The Cu(4)-F(5) bond length is 1.99 Å. The Cu(4)-F(7) bond length is 2.03 Å. The Cu(4)-F(8) bond length is 2.22 Å. The Cu(4)-F(9) bond length is 2.34 Å. In the fifth Cu site, Cu(5) is bonded to one O(1), one F(1), one F(3), one F(4), and one F(9) atom to form distorted CuOF4 square pyramids that share  a cornercorner with one Mg(1)OF5 octahedra, corners with two equivalent Cu(1)OF5 octahedra,  an edgeedge with one Mg(1)OF5 octahedra,  an edgeedge with one Cu(4)OF5 octahedra, and  an edgeedge with one Cu(2)OF4 square pyramid. The corner-sharing octahedral tilt angles range from 51-80°. The Cu(5)-O(1) bond length is 1.93 Å. The Cu(5)-F(1) bond length is 2.10 Å. The Cu(5)-F(3) bond length is 2.09 Å. The Cu(5)-F(4) bond length is 1.99 Å. The Cu(5)-F(9) bond length is 2.12 Å. In the sixth Cu site, Cu(6) is bonded in a 5-coordinate geometry to one O(2), one F(5), one F(6), one F(8), and one F(9) atom. The Cu(6)-O(2) bond length is 1.83 Å. The Cu(6)-F(5) bond length is 2.08 Å. The Cu(6)-F(6) bond length is 2.38 Å. The Cu(6)-F(8) bond length is 1.95 Å. The Cu(6)-F(9) bond length is 2.06 Å. There are two inequivalent O sites. In the first O site, O(1) is bonded in a trigonal pyramidal geometry to one Mg(1), one Cu(3), one Cu(4), and one Cu(5) atom. In the second O site, O(2) is bonded in a trigonal planar geometry to one Cu(1), one Cu(2), and one Cu(6) atom. There are ten inequivalent F sites. In the first F site, F(1) is bonded in a distorted rectangular see-saw-like geometry to one Mg(1), one Cu(1), one Cu(3), and one Cu(5) atom. In the second F site, F(2) is bonded in a bent 120 degrees geometry to one Cu(1) and one Cu(3) atom. In the third F site, F(3) is bonded in a distorted trigonal planar geometry to one Cu(2), one Cu(3), and one Cu(5) atom. In the fourth F site, F(4) is bonded in a distorted trigonal planar geometry to one Cu(1), one Cu(2), and one Cu(5) atom. In the fifth F site, F(5) is bonded in a trigonal non-coplanar geometry to one Mg(1), one Cu(4), and one Cu(6) atom. In the sixth F site, F(6) is bonded in a 3-coordinate geometry to one Mg(1), one Cu(3), and one Cu(6) atom. In the seventh F site, F(7) is bonded in a distorted trigonal planar geometry to one Cu(1), one Cu(2), and one Cu(4) atom. In the eighth F site, F(8) is bonded in a distorted trigonal planar geometry to one Cu(2), one Cu(4), and one Cu(6) atom. In the ninth F site, F(9) is bonded in a rectangular see-saw-like geometry to one Mg(1), one Cu(4), one Cu(5), and one Cu(6) atom. In the tenth F site, F(10) is bonded in a distorted L-shaped geometry to one Mg(1), one Cu(1), and one Cu(4) atom.