MgCo4(CuO4)2 crystallizes in the triclinic P1 space group. Mg(1) is bonded to one O(1), one O(2), one O(4), one O(5), one O(7), and one O(8) atom to form MgO6 octahedra that share corners with six equivalent Co(2)O6 octahedra, edges with two equivalent Co(1)O6 octahedra, edges with two equivalent Co(3)O6 octahedra, and edges with two equivalent Co(4)O6 octahedra. The corner-sharing octahedral tilt angles range from 12-13°. There are four inequivalent Co sites. In the first Co site, Co(1) is bonded to one O(1), one O(2), one O(3), one O(6), one O(7), and one O(8) atom to form CoO6 octahedra that share edges with two equivalent Mg(1)O6 octahedra, edges with two equivalent Co(2)O6 octahedra, edges with two equivalent Co(3)O6 octahedra, and edges with two equivalent Co(4)O6 octahedra. In the second Co site, Co(2) is bonded to one O(1), one O(2), one O(4), one O(5), one O(7), and one O(8) atom to form distorted CoO6 octahedra that share corners with six equivalent Mg(1)O6 octahedra, edges with two equivalent Co(1)O6 octahedra, edges with two equivalent Co(3)O6 octahedra, and edges with two equivalent Co(4)O6 octahedra. The corner-sharing octahedral tilt angles range from 12-13°. In the third Co site, Co(3) is bonded to one O(1), one O(3), one O(4), one O(5), one O(6), and one O(8) atom to form CoO6 octahedra that share edges with two equivalent Mg(1)O6 octahedra, edges with two equivalent Co(1)O6 octahedra, edges with two equivalent Co(2)O6 octahedra, and edges with two equivalent Co(4)O6 octahedra. In the fourth Co site, Co(4) is bonded to one O(2), one O(3), one O(4), one O(5), one O(6), and one O(7) atom to form CoO6 octahedra that share edges with two equivalent Mg(1)O6 octahedra, edges with two equivalent Co(1)O6 octahedra, edges with two equivalent Co(2)O6 octahedra, and edges with two equivalent Co(3)O6 octahedra. There are two inequivalent Cu sites. In the first Cu site, Cu(1) is bonded in a 2-coordinate geometry to one O(5), one O(6), one O(7), and one O(8) atom. In the second Cu site, Cu(2) is bonded in a distorted bent 150 degrees geometry to one O(1), one O(2), one O(3), and one O(4) atom. There are eight inequivalent O sites. In the first O site, O(1) is bonded in a 5-coordinate geometry to one Mg(1), one Co(1), one Co(2), one Co(3), and one Cu(2) atom. In the second O site, O(2) is bonded to one Mg(1), one Co(1), one Co(2), one Co(4), and one Cu(2) atom to form distorted OMgCo3Cu trigonal bipyramids that share  a cornercorner with one O(8)MgCo3Cu trigonal bipyramid,  a cornercorner with one O(3)Co3Cu trigonal pyramid, corners with two equivalent O(6)Co3Cu trigonal pyramids,  an edgeedge with one O(8)MgCo3Cu trigonal bipyramid, and  an edgeedge with one O(3)Co3Cu trigonal pyramid. In the third O site, O(3) is bonded to one Co(1), one Co(3), one Co(4), and one Cu(2) atom to form OCo3Cu trigonal pyramids that share  a cornercorner with one O(2)MgCo3Cu trigonal bipyramid, corners with two equivalent O(8)MgCo3Cu trigonal bipyramids, corners with three equivalent O(6)Co3Cu trigonal pyramids, and  an edgeedge with one O(2)MgCo3Cu trigonal bipyramid. In the fourth O site, O(4) is bonded in a 5-coordinate geometry to one Mg(1), one Co(2), one Co(3), one Co(4), and one Cu(2) atom. In the fifth O site, O(5) is bonded in a 5-coordinate geometry to one Mg(1), one Co(2), one Co(3), one Co(4), and one Cu(1) atom. In the sixth O site, O(6) is bonded to one Co(1), one Co(3), one Co(4), and one Cu(1) atom to form OCo3Cu trigonal pyramids that share  a cornercorner with one O(8)MgCo3Cu trigonal bipyramid, corners with two equivalent O(2)MgCo3Cu trigonal bipyramids, corners with three equivalent O(3)Co3Cu trigonal pyramids, and  an edgeedge with one O(8)MgCo3Cu trigonal bipyramid. In the seventh O site, O(7) is bonded in a 5-coordinate geometry to one Mg(1), one Co(1), one Co(2), one Co(4), and one Cu(1) atom. In the eighth O site, O(8) is bonded to one Mg(1), one Co(1), one Co(2), one Co(3), and one Cu(1) atom to form distorted OMgCo3Cu trigonal bipyramids that share  a cornercorner with one O(2)MgCo3Cu trigonal bipyramid,  a cornercorner with one O(6)Co3Cu trigonal pyramid, corners with two equivalent O(3)Co3Cu trigonal pyramids,  an edgeedge with one O(2)MgCo3Cu trigonal bipyramid, and  an edgeedge with one O(6)Co3Cu trigonal pyramid.
MgCo4(CuO4)2 crystallizes in the triclinic P1 space group. Mg(1) is bonded to one O(1), one O(2), one O(4), one O(5), one O(7), and one O(8) atom to form MgO6 octahedra that share corners with six equivalent Co(2)O6 octahedra, edges with two equivalent Co(1)O6 octahedra, edges with two equivalent Co(3)O6 octahedra, and edges with two equivalent Co(4)O6 octahedra. The corner-sharing octahedral tilt angles range from 12-13°. The Mg(1)-O(1) bond length is 2.05 Å. The Mg(1)-O(2) bond length is 2.11 Å. The Mg(1)-O(4) bond length is 2.11 Å. The Mg(1)-O(5) bond length is 2.11 Å. The Mg(1)-O(7) bond length is 2.05 Å. The Mg(1)-O(8) bond length is 2.12 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(3), one O(6), one O(7), and one O(8) atom to form CoO6 octahedra that share edges with two equivalent Mg(1)O6 octahedra, edges with two equivalent Co(2)O6 octahedra, edges with two equivalent Co(3)O6 octahedra, and edges with two equivalent Co(4)O6 octahedra. The Co(1)-O(1) bond length is 1.95 Å. The Co(1)-O(2) bond length is 1.94 Å. The Co(1)-O(3) bond length is 1.90 Å. The Co(1)-O(6) bond length is 1.90 Å. The Co(1)-O(7) bond length is 1.95 Å. The Co(1)-O(8) bond length is 1.94 Å. In the second Co site, Co(2) is bonded to one O(1), one O(2), one O(4), one O(5), one O(7), and one O(8) atom to form distorted CoO6 octahedra that share corners with six equivalent Mg(1)O6 octahedra, edges with two equivalent Co(1)O6 octahedra, edges with two equivalent Co(3)O6 octahedra, and edges with two equivalent Co(4)O6 octahedra. The corner-sharing octahedral tilt angles range from 12-13°. The Co(2)-O(1) bond length is 2.10 Å. The Co(2)-O(2) bond length is 2.29 Å. The Co(2)-O(4) bond length is 2.06 Å. The Co(2)-O(5) bond length is 2.06 Å. The Co(2)-O(7) bond length is 2.11 Å. The Co(2)-O(8) bond length is 2.27 Å. In the third Co site, Co(3) is bonded to one O(1), one O(3), one O(4), one O(5), one O(6), and one O(8) atom to form CoO6 octahedra that share edges with two equivalent Mg(1)O6 octahedra, edges with two equivalent Co(1)O6 octahedra, edges with two equivalent Co(2)O6 octahedra, and edges with two equivalent Co(4)O6 octahedra. The Co(3)-O(1) bond length is 1.92 Å. The Co(3)-O(3) bond length is 1.91 Å. The Co(3)-O(4) bond length is 1.94 Å. The Co(3)-O(5) bond length is 2.00 Å. The Co(3)-O(6) bond length is 1.90 Å. The Co(3)-O(8) bond length is 1.95 Å. In the fourth Co site, Co(4) is bonded to one O(2), one O(3), one O(4), one O(5), one O(6), and one O(7) atom to form CoO6 octahedra that share edges with two equivalent Mg(1)O6 octahedra, edges with two equivalent Co(1)O6 octahedra, edges with two equivalent Co(2)O6 octahedra, and edges with two equivalent Co(3)O6 octahedra. The Co(4)-O(2) bond length is 1.95 Å. The Co(4)-O(3) bond length is 1.90 Å. The Co(4)-O(4) bond length is 2.00 Å. The Co(4)-O(5) bond length is 1.94 Å. The Co(4)-O(6) bond length is 1.91 Å. The Co(4)-O(7) bond length is 1.92 Å. There are two inequivalent Cu sites. In the first Cu site, Cu(1) is bonded in a 2-coordinate geometry to one O(5), one O(6), one O(7), and one O(8) atom. The Cu(1)-O(5) bond length is 2.57 Å. The Cu(1)-O(6) bond length is 1.82 Å. The Cu(1)-O(7) bond length is 2.55 Å. The Cu(1)-O(8) bond length is 1.85 Å. In the second Cu site, Cu(2) is bonded in a distorted bent 150 degrees geometry to one O(1), one O(2), one O(3), and one O(4) atom. The Cu(2)-O(1) bond length is 2.57 Å. The Cu(2)-O(2) bond length is 1.85 Å. The Cu(2)-O(3) bond length is 1.82 Å. The Cu(2)-O(4) bond length is 2.58 Å. There are eight inequivalent O sites. In the first O site, O(1) is bonded in a 5-coordinate geometry to one Mg(1), one Co(1), one Co(2), one Co(3), and one Cu(2) atom. In the second O site, O(2) is bonded to one Mg(1), one Co(1), one Co(2), one Co(4), and one Cu(2) atom to form distorted OMgCo3Cu trigonal bipyramids that share  a cornercorner with one O(8)MgCo3Cu trigonal bipyramid,  a cornercorner with one O(3)Co3Cu trigonal pyramid, corners with two equivalent O(6)Co3Cu trigonal pyramids,  an edgeedge with one O(8)MgCo3Cu trigonal bipyramid, and  an edgeedge with one O(3)Co3Cu trigonal pyramid. In the third O site, O(3) is bonded to one Co(1), one Co(3), one Co(4), and one Cu(2) atom to form OCo3Cu trigonal pyramids that share  a cornercorner with one O(2)MgCo3Cu trigonal bipyramid, corners with two equivalent O(8)MgCo3Cu trigonal bipyramids, corners with three equivalent O(6)Co3Cu trigonal pyramids, and  an edgeedge with one O(2)MgCo3Cu trigonal bipyramid. In the fourth O site, O(4) is bonded in a 5-coordinate geometry to one Mg(1), one Co(2), one Co(3), one Co(4), and one Cu(2) atom. In the fifth O site, O(5) is bonded in a 5-coordinate geometry to one Mg(1), one Co(2), one Co(3), one Co(4), and one Cu(1) atom. In the sixth O site, O(6) is bonded to one Co(1), one Co(3), one Co(4), and one Cu(1) atom to form OCo3Cu trigonal pyramids that share  a cornercorner with one O(8)MgCo3Cu trigonal bipyramid, corners with two equivalent O(2)MgCo3Cu trigonal bipyramids, corners with three equivalent O(3)Co3Cu trigonal pyramids, and  an edgeedge with one O(8)MgCo3Cu trigonal bipyramid. In the seventh O site, O(7) is bonded in a 5-coordinate geometry to one Mg(1), one Co(1), one Co(2), one Co(4), and one Cu(1) atom. In the eighth O site, O(8) is bonded to one Mg(1), one Co(1), one Co(2), one Co(3), and one Cu(1) atom to form distorted OMgCo3Cu trigonal bipyramids that share  a cornercorner with one O(2)MgCo3Cu trigonal bipyramid,  a cornercorner with one O(6)Co3Cu trigonal pyramid, corners with two equivalent O(3)Co3Cu trigonal pyramids,  an edgeedge with one O(2)MgCo3Cu trigonal bipyramid, and  an edgeedge with one O(6)Co3Cu trigonal pyramid.