MgCrO2 crystallizes in the triclinic P-1 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 Mg(2)O4 tetrahedra, corners with two equivalent Cr(2)O5 trigonal bipyramids, edges with two equivalent Mg(1)O5 trigonal bipyramids, and  a faceface with one Cr(2)O5 trigonal bipyramid. In the second Mg site, Mg(2) is bonded to one O(3), one O(4), and two equivalent O(2) atoms to form MgO4 tetrahedra that share corners with two equivalent Mg(2)O4 tetrahedra, corners with four equivalent Mg(1)O5 trigonal bipyramids, corners with four equivalent Cr(2)O5 trigonal bipyramids, and  an edgeedge with one Cr(2)O5 trigonal bipyramid. There are two inequivalent Cr sites. In the first Cr site, Cr(1) is bonded in a rectangular see-saw-like 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 two equivalent O(4) atoms to form distorted CrO5 trigonal bipyramids that share corners with four equivalent Mg(2)O4 tetrahedra, corners with two equivalent Mg(1)O5 trigonal bipyramids,  an edgeedge with one Mg(2)O4 tetrahedra, edges with two equivalent Cr(2)O5 trigonal bipyramids, 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 distorted OMgCr3 tetrahedra that share corners with two equivalent O(1)MgCr3 tetrahedra, corners with four equivalent O(3)Mg3Cr2 trigonal bipyramids,  an edgeedge with one O(3)Mg3Cr2 trigonal bipyramid, and edges with two equivalent O(4)Mg3Cr2 trigonal bipyramids. 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 distorted OMg3Cr2 trigonal bipyramids that share corners with four equivalent O(1)MgCr3 tetrahedra, corners with three equivalent O(4)Mg3Cr2 trigonal bipyramids,  an edgeedge with one O(1)MgCr3 tetrahedra,  an edgeedge with one O(4)Mg3Cr2 trigonal bipyramid, and edges with two equivalent O(3)Mg3Cr2 trigonal bipyramids. In the fourth O site, O(4) is bonded to one Mg(2), two equivalent Mg(1), and two equivalent Cr(2) atoms to form distorted OMg3Cr2 trigonal bipyramids that share corners with three equivalent O(3)Mg3Cr2 trigonal bipyramids, edges with two equivalent O(1)MgCr3 tetrahedra,  an edgeedge with one O(3)Mg3Cr2 trigonal bipyramid, and edges with two equivalent O(4)Mg3Cr2 trigonal bipyramids.
MgCrO2 crystallizes in the triclinic P-1 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 Mg(2)O4 tetrahedra, corners with two equivalent Cr(2)O5 trigonal bipyramids, edges with two equivalent Mg(1)O5 trigonal bipyramids, and  a faceface with one Cr(2)O5 trigonal bipyramid. The Mg(1)-O(1) bond length is 1.99 Å. Both Mg(1)-O(3) bond lengths are 2.11 Å. There is one shorter (2.12 Å) and one longer (2.13 Å) Mg(1)-O(4) bond length. In the second Mg site, Mg(2) is bonded to one O(3), one O(4), and two equivalent O(2) atoms to form MgO4 tetrahedra that share corners with two equivalent Mg(2)O4 tetrahedra, corners with four equivalent Mg(1)O5 trigonal bipyramids, corners with four equivalent Cr(2)O5 trigonal bipyramids, and  an edgeedge with one Cr(2)O5 trigonal bipyramid. The Mg(2)-O(3) bond length is 1.98 Å. The Mg(2)-O(4) bond length is 1.98 Å. Both Mg(2)-O(2) bond lengths are 1.98 Å. There are two inequivalent Cr sites. In the first Cr site, Cr(1) is bonded in a rectangular see-saw-like geometry to two equivalent O(1) and two equivalent O(3) atoms. Both Cr(1)-O(1) bond lengths are 1.98 Å. Both Cr(1)-O(3) bond lengths are 2.19 Å. In the second Cr site, Cr(2) is bonded to one O(1), two equivalent O(2), and two equivalent O(4) atoms to form distorted CrO5 trigonal bipyramids that share corners with four equivalent Mg(2)O4 tetrahedra, corners with two equivalent Mg(1)O5 trigonal bipyramids,  an edgeedge with one Mg(2)O4 tetrahedra, edges with two equivalent Cr(2)O5 trigonal bipyramids, and  a faceface with one Mg(1)O5 trigonal bipyramid. The Cr(2)-O(1) bond length is 2.30 Å. Both Cr(2)-O(2) bond lengths are 2.09 Å. There is one shorter (2.19 Å) and one longer (2.20 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 distorted OMgCr3 tetrahedra that share corners with two equivalent O(1)MgCr3 tetrahedra, corners with four equivalent O(3)Mg3Cr2 trigonal bipyramids,  an edgeedge with one O(3)Mg3Cr2 trigonal bipyramid, and edges with two equivalent O(4)Mg3Cr2 trigonal bipyramids. 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 distorted OMg3Cr2 trigonal bipyramids that share corners with four equivalent O(1)MgCr3 tetrahedra, corners with three equivalent O(4)Mg3Cr2 trigonal bipyramids,  an edgeedge with one O(1)MgCr3 tetrahedra,  an edgeedge with one O(4)Mg3Cr2 trigonal bipyramid, and edges with two equivalent O(3)Mg3Cr2 trigonal bipyramids. In the fourth O site, O(4) is bonded to one Mg(2), two equivalent Mg(1), and two equivalent Cr(2) atoms to form distorted OMg3Cr2 trigonal bipyramids that share corners with three equivalent O(3)Mg3Cr2 trigonal bipyramids, edges with two equivalent O(1)MgCr3 tetrahedra,  an edgeedge with one O(3)Mg3Cr2 trigonal bipyramid, and edges with two equivalent O(4)Mg3Cr2 trigonal bipyramids.