MgCrO2 crystallizes in the monoclinic C2/m space group. There are two inequivalent Mg sites. In the first Mg site, Mg(1) is bonded to one O(1), two equivalent O(3), and two equivalent O(4) atoms to form distorted MgO5 trigonal bipyramids that share corners with four equivalent Cr(2)O6 octahedra, edges with two equivalent Mg(1)O5 trigonal bipyramids, and  a faceface with one Cr(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 44-52°. In the second Mg site, Mg(2) is bonded in a distorted trigonal non-coplanar geometry to one O(3) and two equivalent O(2) atoms. There are two inequivalent Cr sites. In the first Cr site, Cr(1) is bonded in a square co-planar geometry to two equivalent O(1) and two equivalent O(3) atoms. In the second Cr site, Cr(2) is bonded to one O(1), two equivalent O(2), and three equivalent O(4) atoms to form CrO6 octahedra that share corners with four equivalent Mg(1)O5 trigonal bipyramids, edges with four equivalent Cr(2)O6 octahedra, and  a faceface with one Mg(1)O5 trigonal bipyramid. There are four inequivalent O sites. In the first O site, O(1) is bonded to one Mg(1), one Cr(2), and two equivalent Cr(1) atoms to form OMgCr3 tetrahedra that share corners with two equivalent O(1)MgCr3 tetrahedra, corners with four equivalent O(3)Mg3Cr2 trigonal bipyramids, and  an edgeedge with one O(3)Mg3Cr2 trigonal bipyramid. In the second O site, O(2) is bonded in a rectangular see-saw-like geometry to two equivalent Mg(2) and two equivalent Cr(2) atoms. In the third O site, O(3) is bonded to one Mg(2), two equivalent Mg(1), and two equivalent Cr(1) atoms to form OMg3Cr2 trigonal bipyramids that share corners with four equivalent O(1)MgCr3 tetrahedra,  an edgeedge with one O(1)MgCr3 tetrahedra, and edges with two equivalent O(3)Mg3Cr2 trigonal bipyramids. In the fourth O site, O(4) is bonded in a 5-coordinate geometry to two equivalent Mg(1) and three equivalent Cr(2) atoms.
MgCrO2 crystallizes in the monoclinic C2/m space group. There are two inequivalent Mg sites. In the first Mg site, Mg(1) is bonded to one O(1), two equivalent O(3), and two equivalent O(4) atoms to form distorted MgO5 trigonal bipyramids that share corners with four equivalent Cr(2)O6 octahedra, edges with two equivalent Mg(1)O5 trigonal bipyramids, and  a faceface with one Cr(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 44-52°. The Mg(1)-O(1) bond length is 2.12 Å. Both Mg(1)-O(3) bond lengths are 2.06 Å. Both Mg(1)-O(4) bond lengths are 2.20 Å. In the second Mg site, Mg(2) is bonded in a distorted trigonal non-coplanar geometry to one O(3) and two equivalent O(2) atoms. The Mg(2)-O(3) bond length is 2.07 Å. Both Mg(2)-O(2) bond lengths are 2.03 Å. There are two inequivalent Cr sites. In the first Cr site, Cr(1) is bonded in a square co-planar geometry to two equivalent O(1) and two equivalent O(3) atoms. Both Cr(1)-O(1) bond lengths are 2.00 Å. Both Cr(1)-O(3) bond lengths are 2.12 Å. In the second Cr site, Cr(2) is bonded to one O(1), two equivalent O(2), and three equivalent O(4) atoms to form CrO6 octahedra that share corners with four equivalent Mg(1)O5 trigonal bipyramids, edges with four equivalent Cr(2)O6 octahedra, and  a faceface with one Mg(1)O5 trigonal bipyramid. The Cr(2)-O(1) bond length is 1.96 Å. Both Cr(2)-O(2) bond lengths are 2.06 Å. There are two shorter (2.09 Å) and one longer (2.11 Å) Cr(2)-O(4) bond length. There are four inequivalent O sites. In the first O site, O(1) is bonded to one Mg(1), one Cr(2), and two equivalent Cr(1) atoms to form OMgCr3 tetrahedra that share corners with two equivalent O(1)MgCr3 tetrahedra, corners with four equivalent O(3)Mg3Cr2 trigonal bipyramids, and  an edgeedge with one O(3)Mg3Cr2 trigonal bipyramid. In the second O site, O(2) is bonded in a rectangular see-saw-like geometry to two equivalent Mg(2) and two equivalent Cr(2) atoms. In the third O site, O(3) is bonded to one Mg(2), two equivalent Mg(1), and two equivalent Cr(1) atoms to form OMg3Cr2 trigonal bipyramids that share corners with four equivalent O(1)MgCr3 tetrahedra,  an edgeedge with one O(1)MgCr3 tetrahedra, and edges with two equivalent O(3)Mg3Cr2 trigonal bipyramids. In the fourth O site, O(4) is bonded in a 5-coordinate geometry to two equivalent Mg(1) and three equivalent Cr(2) atoms.