Rb4Mg(CoO3)2 crystallizes in the monoclinic Cm space group. There are two inequivalent Rb sites. In the first Rb site, Rb(1) is bonded in a 7-coordinate geometry to one Mg(1), one O(3), one O(4), two equivalent O(1), and two equivalent O(2) atoms. In the second Rb site, Rb(2) is bonded in a 4-coordinate geometry to two equivalent O(1) and two equivalent O(2) atoms. Mg(1) is bonded in a linear geometry to two equivalent Rb(1), one O(3), and one O(4) atom. There are two inequivalent Co sites. In the first Co site, Co(1) is bonded to one O(3), two equivalent O(1), and two equivalent O(2) atoms to form distorted edge-sharing CoO5 trigonal bipyramids. In the second Co site, Co(2) is bonded to one O(4), two equivalent O(1), and two equivalent O(2) atoms to form distorted edge-sharing CoO5 trigonal bipyramids. There are four inequivalent O sites. In the first O site, O(1) is bonded in a 6-coordinate geometry to two equivalent Rb(1), two equivalent Rb(2), one Co(1), and one Co(2) atom. In the second O site, O(2) is bonded in a 6-coordinate geometry to two equivalent Rb(1), two equivalent Rb(2), one Co(1), and one Co(2) atom. In the third O site, O(3) is bonded in a bent 120 degrees geometry to two equivalent Rb(1), one Mg(1), and one Co(1) atom. In the fourth O site, O(4) is bonded in a distorted bent 150 degrees geometry to two equivalent Rb(1), one Mg(1), and one Co(2) atom.
Rb4Mg(CoO3)2 crystallizes in the monoclinic Cm space group. There are two inequivalent Rb sites. In the first Rb site, Rb(1) is bonded in a 7-coordinate geometry to one Mg(1), one O(3), one O(4), two equivalent O(1), and two equivalent O(2) atoms. The Rb(1)-Mg(1) bond length is 3.03 Å. The Rb(1)-O(3) bond length is 3.40 Å. The Rb(1)-O(4) bond length is 3.39 Å. There is one shorter (2.72 Å) and one longer (2.82 Å) Rb(1)-O(1) bond length. There is one shorter (2.74 Å) and one longer (3.09 Å) Rb(1)-O(2) bond length. In the second Rb site, Rb(2) is bonded in a 4-coordinate geometry to two equivalent O(1) and two equivalent O(2) atoms. There is one shorter (2.83 Å) and one longer (2.85 Å) Rb(2)-O(1) bond length. There is one shorter (2.76 Å) and one longer (3.00 Å) Rb(2)-O(2) bond length. Mg(1) is bonded in a linear geometry to two equivalent Rb(1), one O(3), and one O(4) atom. The Mg(1)-O(3) bond length is 1.83 Å. The Mg(1)-O(4) bond length is 1.83 Å. There are two inequivalent Co sites. In the first Co site, Co(1) is bonded to one O(3), two equivalent O(1), and two equivalent O(2) atoms to form distorted edge-sharing CoO5 trigonal bipyramids. The Co(1)-O(3) bond length is 1.92 Å. Both Co(1)-O(1) bond lengths are 2.01 Å. Both Co(1)-O(2) bond lengths are 2.06 Å. In the second Co site, Co(2) is bonded to one O(4), two equivalent O(1), and two equivalent O(2) atoms to form distorted edge-sharing CoO5 trigonal bipyramids. The Co(2)-O(4) bond length is 1.92 Å. Both Co(2)-O(1) bond lengths are 2.03 Å. Both Co(2)-O(2) bond lengths are 2.05 Å. There are four inequivalent O sites. In the first O site, O(1) is bonded in a 6-coordinate geometry to two equivalent Rb(1), two equivalent Rb(2), one Co(1), and one Co(2) atom. In the second O site, O(2) is bonded in a 6-coordinate geometry to two equivalent Rb(1), two equivalent Rb(2), one Co(1), and one Co(2) atom. In the third O site, O(3) is bonded in a bent 120 degrees geometry to two equivalent Rb(1), one Mg(1), and one Co(1) atom. In the fourth O site, O(4) is bonded in a distorted bent 150 degrees geometry to two equivalent Rb(1), one Mg(1), and one Co(2) atom.