Mg(CoO2)4 crystallizes in the trigonal R-3m space group. Mg(1) is bonded to six equivalent O(1) atoms to form MgO6 octahedra that share corners with six equivalent Co(2)O6 octahedra and edges with six equivalent Co(1)O6 octahedra. The corner-sharing octahedral tilt angles are 11°. There are two inequivalent Co sites. In the first Co site, Co(1) is bonded to two equivalent O(2) and four equivalent O(1) atoms to form CoO6 octahedra that share edges with two equivalent Mg(1)O6 octahedra, edges with two equivalent Co(2)O6 octahedra, and edges with four equivalent Co(1)O6 octahedra. In the second Co site, Co(2) is bonded to six equivalent O(1) atoms to form CoO6 octahedra that share corners with six equivalent Mg(1)O6 octahedra and edges with six equivalent Co(1)O6 octahedra. The corner-sharing octahedral tilt angles are 11°. There are two inequivalent O sites. In the first O site, O(1) is bonded in a rectangular see-saw-like geometry to one Mg(1), one Co(2), and two equivalent Co(1) atoms. In the second O site, O(2) is bonded in a distorted trigonal non-coplanar geometry to three equivalent Co(1) atoms.
Mg(CoO2)4 crystallizes in the trigonal R-3m space group. Mg(1) is bonded to six equivalent O(1) atoms to form MgO6 octahedra that share corners with six equivalent Co(2)O6 octahedra and edges with six equivalent Co(1)O6 octahedra. The corner-sharing octahedral tilt angles are 11°. All Mg(1)-O(1) bond lengths are 2.14 Å. There are two inequivalent Co sites. In the first Co site, Co(1) is bonded to two equivalent O(2) and four equivalent O(1) atoms to form CoO6 octahedra that share edges with two equivalent Mg(1)O6 octahedra, edges with two equivalent Co(2)O6 octahedra, and edges with four equivalent Co(1)O6 octahedra. Both Co(1)-O(2) bond lengths are 1.86 Å. All Co(1)-O(1) bond lengths are 1.89 Å. In the second Co site, Co(2) is bonded to six equivalent O(1) atoms to form CoO6 octahedra that share corners with six equivalent Mg(1)O6 octahedra and edges with six equivalent Co(1)O6 octahedra. The corner-sharing octahedral tilt angles are 11°. All Co(2)-O(1) bond lengths are 1.94 Å. There are two inequivalent O sites. In the first O site, O(1) is bonded in a rectangular see-saw-like geometry to one Mg(1), one Co(2), and two equivalent Co(1) atoms. In the second O site, O(2) is bonded in a distorted trigonal non-coplanar geometry to three equivalent Co(1) atoms.