MgCo2(SbO3)4 crystallizes in the monoclinic Cm space group. Mg(1) is bonded in a 4-coordinate geometry to one O(2), one O(5), and two equivalent O(3) atoms. There are two inequivalent Co sites. In the first Co site, Co(1) is bonded in a 5-coordinate geometry to one O(4), two equivalent O(3), and two equivalent O(6) atoms. In the second Co site, Co(2) is bonded in a 5-coordinate geometry to one O(5), one O(7), one O(9), and two equivalent O(8) atoms. There are four inequivalent Sb sites. In the first Sb site, Sb(1) is bonded in a 5-coordinate geometry to one O(9), two equivalent O(3), and two equivalent O(8) atoms. In the second Sb site, Sb(2) is bonded to one O(1), two equivalent O(6), and two equivalent O(8) atoms to form distorted corner-sharing SbO5 trigonal bipyramids. The corner-sharing octahedral tilt angles range from 38-52°. In the third Sb site, Sb(3) is bonded to one O(1), one O(2), one O(4), one O(7), and two equivalent O(6) atoms to form SbO6 octahedra that share corners with three equivalent Sb(2)O5 trigonal bipyramids and  an edgeedge with one Sb(4)O6 octahedra. In the fourth Sb site, Sb(4) is bonded to one O(2), one O(4), one O(5), one O(9), and two equivalent O(3) atoms to form edge-sharing SbO6 octahedra. There are nine inequivalent O sites. In the first O site, O(1) is bonded in a bent 150 degrees geometry to one Sb(2) and one Sb(3) atom. In the second O site, O(2) is bonded in a T-shaped geometry to one Mg(1), one Sb(3), and one Sb(4) atom. In the third O site, O(3) is bonded in a 4-coordinate geometry to one Mg(1), one Co(1), one Sb(1), and one Sb(4) atom. In the fourth O site, O(4) is bonded in a distorted trigonal planar geometry to one Co(1), one Sb(3), and one Sb(4) atom. In the fifth O site, O(5) is bonded in a distorted T-shaped geometry to one Mg(1), one Co(2), and one Sb(4) atom. In the sixth O site, O(6) is bonded in a trigonal planar geometry to one Co(1), one Sb(2), and one Sb(3) atom. In the seventh O site, O(7) is bonded in a water-like geometry to one Co(2) and one Sb(3) atom. In the eighth O site, O(8) is bonded in a trigonal planar geometry to one Co(2), one Sb(1), and one Sb(2) atom. In the ninth O site, O(9) is bonded in a 3-coordinate geometry to one Co(2), one Sb(1), and one Sb(4) atom.
MgCo2(SbO3)4 crystallizes in the monoclinic Cm space group. Mg(1) is bonded in a 4-coordinate geometry to one O(2), one O(5), and two equivalent O(3) atoms. The Mg(1)-O(2) bond length is 2.01 Å. The Mg(1)-O(5) bond length is 1.96 Å. Both Mg(1)-O(3) bond lengths are 1.95 Å. There are two inequivalent Co sites. In the first Co site, Co(1) is bonded in a 5-coordinate geometry to one O(4), two equivalent O(3), and two equivalent O(6) atoms. The Co(1)-O(4) bond length is 1.97 Å. Both Co(1)-O(3) bond lengths are 2.17 Å. Both Co(1)-O(6) bond lengths are 2.05 Å. In the second Co site, Co(2) is bonded in a 5-coordinate geometry to one O(5), one O(7), one O(9), and two equivalent O(8) atoms. The Co(2)-O(5) bond length is 2.07 Å. The Co(2)-O(7) bond length is 1.94 Å. The Co(2)-O(9) bond length is 2.58 Å. Both Co(2)-O(8) bond lengths are 2.09 Å. There are four inequivalent Sb sites. In the first Sb site, Sb(1) is bonded in a 5-coordinate geometry to one O(9), two equivalent O(3), and two equivalent O(8) atoms. The Sb(1)-O(9) bond length is 1.99 Å. Both Sb(1)-O(3) bond lengths are 2.63 Å. Both Sb(1)-O(8) bond lengths are 2.06 Å. In the second Sb site, Sb(2) is bonded to one O(1), two equivalent O(6), and two equivalent O(8) atoms to form distorted corner-sharing SbO5 trigonal bipyramids. The corner-sharing octahedral tilt angles range from 38-52°. The Sb(2)-O(1) bond length is 1.94 Å. Both Sb(2)-O(6) bond lengths are 2.00 Å. Both Sb(2)-O(8) bond lengths are 2.01 Å. In the third Sb site, Sb(3) is bonded to one O(1), one O(2), one O(4), one O(7), and two equivalent O(6) atoms to form SbO6 octahedra that share corners with three equivalent Sb(2)O5 trigonal bipyramids and  an edgeedge with one Sb(4)O6 octahedra. The Sb(3)-O(1) bond length is 2.04 Å. The Sb(3)-O(2) bond length is 2.01 Å. The Sb(3)-O(4) bond length is 2.11 Å. The Sb(3)-O(7) bond length is 1.91 Å. Both Sb(3)-O(6) bond lengths are 2.07 Å. In the fourth Sb site, Sb(4) is bonded to one O(2), one O(4), one O(5), one O(9), and two equivalent O(3) atoms to form edge-sharing SbO6 octahedra. The Sb(4)-O(2) bond length is 2.09 Å. The Sb(4)-O(4) bond length is 2.03 Å. The Sb(4)-O(5) bond length is 2.00 Å. The Sb(4)-O(9) bond length is 2.00 Å. Both Sb(4)-O(3) bond lengths are 2.00 Å. There are nine inequivalent O sites. In the first O site, O(1) is bonded in a bent 150 degrees geometry to one Sb(2) and one Sb(3) atom. In the second O site, O(2) is bonded in a T-shaped geometry to one Mg(1), one Sb(3), and one Sb(4) atom. In the third O site, O(3) is bonded in a 4-coordinate geometry to one Mg(1), one Co(1), one Sb(1), and one Sb(4) atom. In the fourth O site, O(4) is bonded in a distorted trigonal planar geometry to one Co(1), one Sb(3), and one Sb(4) atom. In the fifth O site, O(5) is bonded in a distorted T-shaped geometry to one Mg(1), one Co(2), and one Sb(4) atom. In the sixth O site, O(6) is bonded in a trigonal planar geometry to one Co(1), one Sb(2), and one Sb(3) atom. In the seventh O site, O(7) is bonded in a water-like geometry to one Co(2) and one Sb(3) atom. In the eighth O site, O(8) is bonded in a trigonal planar geometry to one Co(2), one Sb(1), and one Sb(2) atom. In the ninth O site, O(9) is bonded in a 3-coordinate geometry to one Co(2), one Sb(1), and one Sb(4) atom.