MgCr2(SbO4)2 crystallizes in the monoclinic Cm space group. Mg(1) is bonded to one O(3), one O(6), two equivalent O(1), and two equivalent O(2) atoms to form distorted MgO6 octahedra that share corners with two equivalent Sb(2)O6 octahedra, edges with four equivalent Cr(1)O6 octahedra, and  a faceface with one Sb(2)O6 octahedra. The corner-sharing octahedral tilt angles are 46°. Cr(1) is bonded to one O(1), one O(2), one O(3), one O(4), one O(5), and one O(6) atom to form CrO6 octahedra that share corners with four equivalent Sb(2)O6 octahedra, edges with two equivalent Mg(1)O6 octahedra, and edges with two equivalent Cr(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 34-60°. There are two inequivalent Sb sites. In the first Sb site, Sb(1) is bonded in a 5-coordinate geometry to one O(3), one O(4), one O(5), and two equivalent O(2) atoms. In the second Sb site, Sb(2) is bonded to one O(4), one O(6), two equivalent O(1), and two equivalent O(2) atoms to form SbO6 octahedra that share corners with two equivalent Mg(1)O6 octahedra, corners with eight equivalent Cr(1)O6 octahedra, and  a faceface with one Mg(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 34-60°. There are six inequivalent O sites. In the first O site, O(1) is bonded in a distorted trigonal planar geometry to one Mg(1), one Cr(1), and one Sb(2) atom. In the second O site, O(2) is bonded in a distorted see-saw-like geometry to one Mg(1), one Cr(1), one Sb(1), and one Sb(2) atom. In the third O site, O(3) is bonded in a 4-coordinate geometry to one Mg(1), two equivalent Cr(1), and one Sb(1) atom. In the fourth O site, O(4) is bonded to two equivalent Cr(1), one Sb(1), and one Sb(2) atom to form a mixture of distorted corner and edge-sharing OCr2Sb2 trigonal pyramids. In the fifth O site, O(5) is bonded in a trigonal planar geometry to two equivalent Cr(1) and one Sb(1) atom. In the sixth O site, O(6) is bonded to one Mg(1), two equivalent Cr(1), and one Sb(2) atom to form a mixture of corner and edge-sharing OMgCr2Sb trigonal pyramids.
MgCr2(SbO4)2 crystallizes in the monoclinic Cm space group. Mg(1) is bonded to one O(3), one O(6), two equivalent O(1), and two equivalent O(2) atoms to form distorted MgO6 octahedra that share corners with two equivalent Sb(2)O6 octahedra, edges with four equivalent Cr(1)O6 octahedra, and  a faceface with one Sb(2)O6 octahedra. The corner-sharing octahedral tilt angles are 46°. The Mg(1)-O(3) bond length is 1.98 Å. The Mg(1)-O(6) bond length is 2.03 Å. Both Mg(1)-O(1) bond lengths are 2.10 Å. Both Mg(1)-O(2) bond lengths are 2.15 Å. Cr(1) is bonded to one O(1), one O(2), one O(3), one O(4), one O(5), and one O(6) atom to form CrO6 octahedra that share corners with four equivalent Sb(2)O6 octahedra, edges with two equivalent Mg(1)O6 octahedra, and edges with two equivalent Cr(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 34-60°. The Cr(1)-O(1) bond length is 2.02 Å. The Cr(1)-O(2) bond length is 2.10 Å. The Cr(1)-O(3) bond length is 1.96 Å. The Cr(1)-O(4) bond length is 2.22 Å. The Cr(1)-O(5) bond length is 1.96 Å. The Cr(1)-O(6) bond length is 2.23 Å. There are two inequivalent Sb sites. In the first Sb site, Sb(1) is bonded in a 5-coordinate geometry to one O(3), one O(4), one O(5), and two equivalent O(2) atoms. The Sb(1)-O(3) bond length is 2.59 Å. The Sb(1)-O(4) bond length is 2.43 Å. The Sb(1)-O(5) bond length is 2.02 Å. Both Sb(1)-O(2) bond lengths are 2.13 Å. In the second Sb site, Sb(2) is bonded to one O(4), one O(6), two equivalent O(1), and two equivalent O(2) atoms to form SbO6 octahedra that share corners with two equivalent Mg(1)O6 octahedra, corners with eight equivalent Cr(1)O6 octahedra, and  a faceface with one Mg(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 34-60°. The Sb(2)-O(4) bond length is 2.10 Å. The Sb(2)-O(6) bond length is 2.13 Å. Both Sb(2)-O(1) bond lengths are 2.00 Å. Both Sb(2)-O(2) bond lengths are 2.08 Å. There are six inequivalent O sites. In the first O site, O(1) is bonded in a distorted trigonal planar geometry to one Mg(1), one Cr(1), and one Sb(2) atom. In the second O site, O(2) is bonded in a distorted see-saw-like geometry to one Mg(1), one Cr(1), one Sb(1), and one Sb(2) atom. In the third O site, O(3) is bonded in a 4-coordinate geometry to one Mg(1), two equivalent Cr(1), and one Sb(1) atom. In the fourth O site, O(4) is bonded to two equivalent Cr(1), one Sb(1), and one Sb(2) atom to form a mixture of distorted corner and edge-sharing OCr2Sb2 trigonal pyramids. In the fifth O site, O(5) is bonded in a trigonal planar geometry to two equivalent Cr(1) and one Sb(1) atom. In the sixth O site, O(6) is bonded to one Mg(1), two equivalent Cr(1), and one Sb(2) atom to form a mixture of corner and edge-sharing OMgCr2Sb trigonal pyramids.