MgCd2(CoO3)2 crystallizes in the trigonal R3 space group. Mg(1) is bonded to three equivalent O(1) and three equivalent O(2) atoms to form distorted MgO6 octahedra that share corners with three equivalent Co(2)O6 octahedra, edges with three equivalent Co(1)O6 octahedra, and  a faceface with one Co(2)O6 octahedra. The corner-sharing octahedral tilt angles are 35°. There are two inequivalent Co sites. In the first Co site, Co(1) is bonded to three equivalent O(1) and three equivalent O(2) atoms to form CoO6 octahedra that share corners with three equivalent Co(2)O6 octahedra, edges with three equivalent Mg(1)O6 octahedra, and  a faceface with one Co(2)O6 octahedra. The corner-sharing octahedral tilt angles are 33°. In the second Co site, Co(2) is bonded to three equivalent O(1) and three equivalent O(2) atoms to form CoO6 octahedra that share corners with three equivalent Mg(1)O6 octahedra, corners with three equivalent Co(1)O6 octahedra,  a faceface with one Mg(1)O6 octahedra, and  a faceface with one Co(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 33-35°. There are two inequivalent Cd sites. In the first Cd site, Cd(1) is bonded in a 6-coordinate geometry to three equivalent O(1) and three equivalent O(2) atoms. In the second Cd site, Cd(2) is bonded in a trigonal planar geometry to three equivalent O(2) atoms. There are two inequivalent O sites. In the first O site, O(1) is bonded in a 4-coordinate geometry to one Mg(1), one Co(1), one Co(2), and one Cd(1) atom. In the second O site, O(2) is bonded to one Mg(1), one Co(1), one Co(2), one Cd(1), and one Cd(2) atom to form a mixture of distorted corner and edge-sharing OMgCd2Co2 trigonal bipyramids.
MgCd2(CoO3)2 crystallizes in the trigonal R3 space group. Mg(1) is bonded to three equivalent O(1) and three equivalent O(2) atoms to form distorted MgO6 octahedra that share corners with three equivalent Co(2)O6 octahedra, edges with three equivalent Co(1)O6 octahedra, and  a faceface with one Co(2)O6 octahedra. The corner-sharing octahedral tilt angles are 35°. All Mg(1)-O(1) bond lengths are 2.09 Å. All Mg(1)-O(2) bond lengths are 2.12 Å. There are two inequivalent Co sites. In the first Co site, Co(1) is bonded to three equivalent O(1) and three equivalent O(2) atoms to form CoO6 octahedra that share corners with three equivalent Co(2)O6 octahedra, edges with three equivalent Mg(1)O6 octahedra, and  a faceface with one Co(2)O6 octahedra. The corner-sharing octahedral tilt angles are 33°. All Co(1)-O(1) bond lengths are 1.95 Å. All Co(1)-O(2) bond lengths are 2.02 Å. In the second Co site, Co(2) is bonded to three equivalent O(1) and three equivalent O(2) atoms to form CoO6 octahedra that share corners with three equivalent Mg(1)O6 octahedra, corners with three equivalent Co(1)O6 octahedra,  a faceface with one Mg(1)O6 octahedra, and  a faceface with one Co(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 33-35°. All Co(2)-O(1) bond lengths are 1.92 Å. All Co(2)-O(2) bond lengths are 2.02 Å. There are two inequivalent Cd sites. In the first Cd site, Cd(1) is bonded in a 6-coordinate geometry to three equivalent O(1) and three equivalent O(2) atoms. All Cd(1)-O(1) bond lengths are 2.23 Å. All Cd(1)-O(2) bond lengths are 2.47 Å. In the second Cd site, Cd(2) is bonded in a trigonal planar geometry to three equivalent O(2) atoms. All Cd(2)-O(2) bond lengths are 2.14 Å. There are two inequivalent O sites. In the first O site, O(1) is bonded in a 4-coordinate geometry to one Mg(1), one Co(1), one Co(2), and one Cd(1) atom. In the second O site, O(2) is bonded to one Mg(1), one Co(1), one Co(2), one Cd(1), and one Cd(2) atom to form a mixture of distorted corner and edge-sharing OMgCd2Co2 trigonal bipyramids.