MgCr2O4 crystallizes in the monoclinic P2/m space group. Mg(1) is bonded to two equivalent O(2) and four equivalent O(1) atoms to form MgO6 octahedra that share corners with four equivalent Cr(2)O6 octahedra, edges with two equivalent Mg(1)O6 octahedra, edges with four equivalent Cr(1)O6 octahedra, and faces with two equivalent Cr(2)O6 octahedra. The corner-sharing octahedral tilt angles are 43°. There are two inequivalent Cr sites. In the first Cr site, Cr(1) is bonded to two equivalent O(1) and four equivalent O(2) atoms to form CrO6 octahedra that share corners with eight equivalent Cr(2)O6 octahedra, edges with two equivalent Cr(1)O6 octahedra, and edges with four equivalent Mg(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 48-49°. In the second Cr site, Cr(2) is bonded to two equivalent O(2) and four equivalent O(1) atoms to form CrO6 octahedra that share corners with four equivalent Mg(1)O6 octahedra, corners with eight equivalent Cr(1)O6 octahedra, edges with two equivalent Cr(2)O6 octahedra, and faces with two equivalent Mg(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 43-49°. There are two inequivalent O sites. In the first O site, O(1) is bonded to two equivalent Mg(1), one Cr(1), and two equivalent Cr(2) atoms to form a mixture of distorted corner and edge-sharing OMg2Cr3 square pyramids. In the second O site, O(2) is bonded in a rectangular see-saw-like geometry to one Mg(1), one Cr(2), and two equivalent Cr(1) atoms.
MgCr2O4 crystallizes in the monoclinic P2/m space group. Mg(1) is bonded to two equivalent O(2) and four equivalent O(1) atoms to form MgO6 octahedra that share corners with four equivalent Cr(2)O6 octahedra, edges with two equivalent Mg(1)O6 octahedra, edges with four equivalent Cr(1)O6 octahedra, and faces with two equivalent Cr(2)O6 octahedra. The corner-sharing octahedral tilt angles are 43°. Both Mg(1)-O(2) bond lengths are 1.94 Å. All Mg(1)-O(1) bond lengths are 2.10 Å. There are two inequivalent Cr sites. In the first Cr site, Cr(1) is bonded to two equivalent O(1) and four equivalent O(2) atoms to form CrO6 octahedra that share corners with eight equivalent Cr(2)O6 octahedra, edges with two equivalent Cr(1)O6 octahedra, and edges with four equivalent Mg(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 48-49°. Both Cr(1)-O(1) bond lengths are 2.21 Å. All Cr(1)-O(2) bond lengths are 2.01 Å. In the second Cr site, Cr(2) is bonded to two equivalent O(2) and four equivalent O(1) atoms to form CrO6 octahedra that share corners with four equivalent Mg(1)O6 octahedra, corners with eight equivalent Cr(1)O6 octahedra, edges with two equivalent Cr(2)O6 octahedra, and faces with two equivalent Mg(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 43-49°. Both Cr(2)-O(2) bond lengths are 2.10 Å. All Cr(2)-O(1) bond lengths are 2.08 Å. There are two inequivalent O sites. In the first O site, O(1) is bonded to two equivalent Mg(1), one Cr(1), and two equivalent Cr(2) atoms to form a mixture of distorted corner and edge-sharing OMg2Cr3 square pyramids. In the second O site, O(2) is bonded in a rectangular see-saw-like geometry to one Mg(1), one Cr(2), and two equivalent Cr(1) atoms.