K2Mg(CoO2)2 crystallizes in the monoclinic Cm space group. There are two inequivalent K sites. In the first K site, K(1) is bonded in a 5-coordinate geometry to one O(1), two equivalent O(3), and two equivalent O(4) atoms. In the second K site, K(2) is bonded in a 6-coordinate geometry to one O(3), one O(4), two equivalent O(1), and two equivalent O(2) atoms. Mg(1) is bonded to one O(2), one O(3), and two equivalent O(4) atoms to form MgO4 tetrahedra that share corners with two equivalent Mg(1)O4 tetrahedra and edges with two equivalent Co(1)O4 tetrahedra. There are two inequivalent Co sites. In the first Co site, Co(1) is bonded to one O(1), one O(4), and two equivalent O(3) atoms to form CoO4 tetrahedra that share corners with two equivalent Co(1)O4 tetrahedra and edges with two equivalent Mg(1)O4 tetrahedra. In the second Co site, Co(2) is bonded in a trigonal planar geometry to one O(1) and two equivalent O(2) atoms. There are four inequivalent O sites. In the first O site, O(1) is bonded in a distorted rectangular see-saw-like geometry to one K(1), two equivalent K(2), one Co(1), and one Co(2) atom. In the second O site, O(2) is bonded in a 5-coordinate geometry to two equivalent K(2), one Mg(1), and two equivalent Co(2) atoms. In the third O site, O(3) is bonded in a 6-coordinate geometry to one K(2), two equivalent K(1), one Mg(1), and two equivalent Co(1) atoms. In the fourth O site, O(4) is bonded in a 6-coordinate geometry to one K(2), two equivalent K(1), two equivalent Mg(1), and one Co(1) atom.
K2Mg(CoO2)2 crystallizes in the monoclinic Cm space group. There are two inequivalent K sites. In the first K site, K(1) is bonded in a 5-coordinate geometry to one O(1), two equivalent O(3), and two equivalent O(4) atoms. The K(1)-O(1) bond length is 3.35 Å. Both K(1)-O(3) bond lengths are 2.85 Å. Both K(1)-O(4) bond lengths are 2.95 Å. In the second K site, K(2) is bonded in a 6-coordinate geometry to one O(3), one O(4), two equivalent O(1), and two equivalent O(2) atoms. The K(2)-O(3) bond length is 2.77 Å. The K(2)-O(4) bond length is 2.82 Å. Both K(2)-O(1) bond lengths are 2.54 Å. Both K(2)-O(2) bond lengths are 2.80 Å. Mg(1) is bonded to one O(2), one O(3), and two equivalent O(4) atoms to form MgO4 tetrahedra that share corners with two equivalent Mg(1)O4 tetrahedra and edges with two equivalent Co(1)O4 tetrahedra. The Mg(1)-O(2) bond length is 2.01 Å. The Mg(1)-O(3) bond length is 2.01 Å. Both Mg(1)-O(4) bond lengths are 2.00 Å. There are two inequivalent Co sites. In the first Co site, Co(1) is bonded to one O(1), one O(4), and two equivalent O(3) atoms to form CoO4 tetrahedra that share corners with two equivalent Co(1)O4 tetrahedra and edges with two equivalent Mg(1)O4 tetrahedra. The Co(1)-O(1) bond length is 1.96 Å. The Co(1)-O(4) bond length is 2.05 Å. Both Co(1)-O(3) bond lengths are 2.06 Å. In the second Co site, Co(2) is bonded in a trigonal planar geometry to one O(1) and two equivalent O(2) atoms. The Co(2)-O(1) bond length is 1.78 Å. Both Co(2)-O(2) bond lengths are 1.98 Å. There are four inequivalent O sites. In the first O site, O(1) is bonded in a distorted rectangular see-saw-like geometry to one K(1), two equivalent K(2), one Co(1), and one Co(2) atom. In the second O site, O(2) is bonded in a 5-coordinate geometry to two equivalent K(2), one Mg(1), and two equivalent Co(2) atoms. In the third O site, O(3) is bonded in a 6-coordinate geometry to one K(2), two equivalent K(1), one Mg(1), and two equivalent Co(1) atoms. In the fourth O site, O(4) is bonded in a 6-coordinate geometry to one K(2), two equivalent K(1), two equivalent Mg(1), and one Co(1) atom.