MgCo5O8 is Spinel-like structured and crystallizes in the monoclinic Cm space group. Mg(1) is bonded to one O(5), one O(6), and two equivalent O(4) atoms to form MgO4 tetrahedra that share corners with three equivalent Co(1)O6 octahedra, corners with three equivalent Co(2)O6 octahedra, and corners with six equivalent Co(4)O6 octahedra. The corner-sharing octahedral tilt angles range from 53-64°. There are four inequivalent Co sites. In the first Co site, Co(1) is bonded to one O(2), one O(5), two equivalent O(3), and two equivalent O(4) atoms to form CoO6 octahedra that share corners with three equivalent Mg(1)O4 tetrahedra, corners with three equivalent Co(3)O4 tetrahedra, edges with two equivalent Co(2)O6 octahedra, and edges with four equivalent Co(4)O6 octahedra. In the second Co site, Co(2) is bonded to one O(1), one O(6), two equivalent O(3), and two equivalent O(4) atoms to form CoO6 octahedra that share corners with three equivalent Mg(1)O4 tetrahedra, corners with three equivalent Co(3)O4 tetrahedra, edges with two equivalent Co(1)O6 octahedra, and edges with four equivalent Co(4)O6 octahedra. In the third Co site, Co(3) is bonded to one O(1), one O(2), and two equivalent O(3) atoms to form corner-sharing CoO4 tetrahedra. The corner-sharing octahedral tilt angles range from 53-64°. In the fourth Co site, Co(4) is bonded to one O(1), one O(2), one O(3), one O(4), one O(5), and one O(6) atom to form CoO6 octahedra that share corners with three equivalent Mg(1)O4 tetrahedra, corners with three equivalent Co(3)O4 tetrahedra, 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. There are six inequivalent O sites. In the first O site, O(1) is bonded in a distorted rectangular see-saw-like geometry to one Co(2), one Co(3), and two equivalent Co(4) atoms. In the second O site, O(2) is bonded to one Co(1), one Co(3), and two equivalent Co(4) atoms to form distorted OCo4 tetrahedra that share corners with three equivalent O(5)MgCo3 tetrahedra, corners with two equivalent O(3)Co4 trigonal pyramids, corners with four equivalent O(4)MgCo3 trigonal pyramids, and edges with two equivalent O(3)Co4 trigonal pyramids. In the third O site, O(3) is bonded to one Co(1), one Co(2), one Co(3), and one Co(4) atom to form distorted OCo4 trigonal pyramids that share  a cornercorner with one O(2)Co4 tetrahedra, corners with two equivalent O(5)MgCo3 tetrahedra,  a cornercorner with one O(3)Co4 trigonal pyramid, corners with five equivalent O(4)MgCo3 trigonal pyramids,  an edgeedge with one O(2)Co4 tetrahedra, and  an edgeedge with one O(3)Co4 trigonal pyramid. In the fourth O site, O(4) is bonded to one Mg(1), one Co(1), one Co(2), and one Co(4) atom to form distorted OMgCo3 trigonal pyramids that share  a cornercorner with one O(5)MgCo3 tetrahedra, corners with two equivalent O(2)Co4 tetrahedra,  a cornercorner with one O(4)MgCo3 trigonal pyramid, corners with five equivalent O(3)Co4 trigonal pyramids,  an edgeedge with one O(5)MgCo3 tetrahedra, and  an edgeedge with one O(4)MgCo3 trigonal pyramid. In the fifth O site, O(5) is bonded to one Mg(1), one Co(1), and two equivalent Co(4) atoms to form distorted OMgCo3 tetrahedra that share corners with three equivalent O(2)Co4 tetrahedra, corners with two equivalent O(4)MgCo3 trigonal pyramids, corners with four equivalent O(3)Co4 trigonal pyramids, and edges with two equivalent O(4)MgCo3 trigonal pyramids. In the sixth O site, O(6) is bonded in a distorted rectangular see-saw-like geometry to one Mg(1), one Co(2), and two equivalent Co(4) atoms.
MgCo5O8 is Spinel-like structured and crystallizes in the monoclinic Cm space group. Mg(1) is bonded to one O(5), one O(6), and two equivalent O(4) atoms to form MgO4 tetrahedra that share corners with three equivalent Co(1)O6 octahedra, corners with three equivalent Co(2)O6 octahedra, and corners with six equivalent Co(4)O6 octahedra. The corner-sharing octahedral tilt angles range from 53-64°. The Mg(1)-O(5) bond length is 2.01 Å. The Mg(1)-O(6) bond length is 1.97 Å. Both Mg(1)-O(4) bond lengths are 1.97 Å. There are four inequivalent Co sites. In the first Co site, Co(1) is bonded to one O(2), one O(5), two equivalent O(3), and two equivalent O(4) atoms to form CoO6 octahedra that share corners with three equivalent Mg(1)O4 tetrahedra, corners with three equivalent Co(3)O4 tetrahedra, edges with two equivalent Co(2)O6 octahedra, and edges with four equivalent Co(4)O6 octahedra. The Co(1)-O(2) bond length is 1.95 Å. The Co(1)-O(5) bond length is 1.93 Å. Both Co(1)-O(3) bond lengths are 1.94 Å. Both Co(1)-O(4) bond lengths are 1.94 Å. In the second Co site, Co(2) is bonded to one O(1), one O(6), two equivalent O(3), and two equivalent O(4) atoms to form CoO6 octahedra that share corners with three equivalent Mg(1)O4 tetrahedra, corners with three equivalent Co(3)O4 tetrahedra, edges with two equivalent Co(1)O6 octahedra, and edges with four equivalent Co(4)O6 octahedra. The Co(2)-O(1) bond length is 2.19 Å. The Co(2)-O(6) bond length is 2.15 Å. Both Co(2)-O(3) bond lengths are 1.91 Å. Both Co(2)-O(4) bond lengths are 1.91 Å. In the third Co site, Co(3) is bonded to one O(1), one O(2), and two equivalent O(3) atoms to form corner-sharing CoO4 tetrahedra. The corner-sharing octahedral tilt angles range from 53-64°. The Co(3)-O(1) bond length is 1.96 Å. The Co(3)-O(2) bond length is 2.00 Å. Both Co(3)-O(3) bond lengths are 1.96 Å. In the fourth Co site, Co(4) is bonded to one O(1), one O(2), one O(3), one O(4), one O(5), and one O(6) atom to form CoO6 octahedra that share corners with three equivalent Mg(1)O4 tetrahedra, corners with three equivalent Co(3)O4 tetrahedra, 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(4)-O(1) bond length is 1.90 Å. The Co(4)-O(2) bond length is 1.97 Å. The Co(4)-O(3) bond length is 2.16 Å. The Co(4)-O(4) bond length is 2.13 Å. The Co(4)-O(5) bond length is 1.97 Å. The Co(4)-O(6) bond length is 1.89 Å. There are six inequivalent O sites. In the first O site, O(1) is bonded in a distorted rectangular see-saw-like geometry to one Co(2), one Co(3), and two equivalent Co(4) atoms. In the second O site, O(2) is bonded to one Co(1), one Co(3), and two equivalent Co(4) atoms to form distorted OCo4 tetrahedra that share corners with three equivalent O(5)MgCo3 tetrahedra, corners with two equivalent O(3)Co4 trigonal pyramids, corners with four equivalent O(4)MgCo3 trigonal pyramids, and edges with two equivalent O(3)Co4 trigonal pyramids. In the third O site, O(3) is bonded to one Co(1), one Co(2), one Co(3), and one Co(4) atom to form distorted OCo4 trigonal pyramids that share  a cornercorner with one O(2)Co4 tetrahedra, corners with two equivalent O(5)MgCo3 tetrahedra,  a cornercorner with one O(3)Co4 trigonal pyramid, corners with five equivalent O(4)MgCo3 trigonal pyramids,  an edgeedge with one O(2)Co4 tetrahedra, and  an edgeedge with one O(3)Co4 trigonal pyramid. In the fourth O site, O(4) is bonded to one Mg(1), one Co(1), one Co(2), and one Co(4) atom to form distorted OMgCo3 trigonal pyramids that share  a cornercorner with one O(5)MgCo3 tetrahedra, corners with two equivalent O(2)Co4 tetrahedra,  a cornercorner with one O(4)MgCo3 trigonal pyramid, corners with five equivalent O(3)Co4 trigonal pyramids,  an edgeedge with one O(5)MgCo3 tetrahedra, and  an edgeedge with one O(4)MgCo3 trigonal pyramid. In the fifth O site, O(5) is bonded to one Mg(1), one Co(1), and two equivalent Co(4) atoms to form distorted OMgCo3 tetrahedra that share corners with three equivalent O(2)Co4 tetrahedra, corners with two equivalent O(4)MgCo3 trigonal pyramids, corners with four equivalent O(3)Co4 trigonal pyramids, and edges with two equivalent O(4)MgCo3 trigonal pyramids. In the sixth O site, O(6) is bonded in a distorted rectangular see-saw-like geometry to one Mg(1), one Co(2), and two equivalent Co(4) atoms.