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), one O(4), and two equivalent O(3) atoms to form distorted MgO4 trigonal pyramids that share  a cornercorner with one Cr(2)O5 trigonal bipyramid, corners with two equivalent Mg(1)O4 trigonal pyramids, and  an edgeedge with one Cr(2)O5 trigonal bipyramid. In the second Mg site, Mg(2) is bonded in a rectangular see-saw-like geometry to one O(3), one O(4), and two equivalent O(2) atoms. There are two inequivalent Cr sites. In the first Cr site, Cr(1) is bonded in a 4-coordinate geometry to one O(2), one O(3), and two equivalent O(1) 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  a cornercorner with one Mg(1)O4 trigonal pyramid, edges with two equivalent Cr(2)O5 trigonal bipyramids, and  an edgeedge with one Mg(1)O4 trigonal pyramid. There are four inequivalent O sites. In the first O site, O(1) is bonded in a 4-coordinate geometry to one Mg(1), one Cr(2), and two equivalent Cr(1) atoms. In the second O site, O(2) is bonded to two equivalent Mg(2), one Cr(1), and two equivalent Cr(2) atoms to form distorted OMg2Cr3 trigonal bipyramids that share  a cornercorner with one O(3)Mg3Cr trigonal pyramid, corners with four equivalent O(4)Mg2Cr2 trigonal pyramids, edges with two equivalent O(2)Mg2Cr3 trigonal bipyramids,  an edgeedge with one O(4)Mg2Cr2 trigonal pyramid, and  an edgeedge with one O(3)Mg3Cr trigonal pyramid. In the third O site, O(3) is bonded to one Mg(2), two equivalent Mg(1), and one Cr(1) atom to form distorted OMg3Cr trigonal pyramids that share  a cornercorner with one O(2)Mg2Cr3 trigonal bipyramid, corners with two equivalent O(3)Mg3Cr trigonal pyramids, corners with three equivalent O(4)Mg2Cr2 trigonal pyramids, and  an edgeedge with one O(2)Mg2Cr3 trigonal bipyramid. In the fourth O site, O(4) is bonded to one Mg(1), one Mg(2), and two equivalent Cr(2) atoms to form OMg2Cr2 trigonal pyramids that share corners with four equivalent O(2)Mg2Cr3 trigonal bipyramids, corners with two equivalent O(4)Mg2Cr2 trigonal pyramids, corners with three equivalent O(3)Mg3Cr trigonal pyramids, and  an edgeedge with one O(2)Mg2Cr3 trigonal bipyramid.
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), one O(4), and two equivalent O(3) atoms to form distorted MgO4 trigonal pyramids that share  a cornercorner with one Cr(2)O5 trigonal bipyramid, corners with two equivalent Mg(1)O4 trigonal pyramids, and  an edgeedge with one Cr(2)O5 trigonal bipyramid. The Mg(1)-O(1) bond length is 2.00 Å. The Mg(1)-O(4) bond length is 1.99 Å. There is one shorter (1.99 Å) and one longer (2.01 Å) Mg(1)-O(3) bond length. In the second Mg site, Mg(2) is bonded in a rectangular see-saw-like geometry to one O(3), one O(4), and two equivalent O(2) atoms. The Mg(2)-O(3) bond length is 1.94 Å. The Mg(2)-O(4) bond length is 1.94 Å. There is one shorter (2.04 Å) and one longer (2.09 Å) Mg(2)-O(2) bond length. There are two inequivalent Cr sites. In the first Cr site, Cr(1) is bonded in a 4-coordinate geometry to one O(2), one O(3), and two equivalent O(1) atoms. The Cr(1)-O(2) bond length is 2.27 Å. The Cr(1)-O(3) bond length is 2.13 Å. There is one shorter (2.01 Å) and one longer (2.02 Å) Cr(1)-O(1) bond length. 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  a cornercorner with one Mg(1)O4 trigonal pyramid, edges with two equivalent Cr(2)O5 trigonal bipyramids, and  an edgeedge with one Mg(1)O4 trigonal pyramid. The Cr(2)-O(1) bond length is 2.40 Å. There is one shorter (2.15 Å) and one longer (2.19 Å) Cr(2)-O(2) bond length. There is one shorter (2.07 Å) and one longer (2.08 Å) Cr(2)-O(4) bond length. There are four inequivalent O sites. In the first O site, O(1) is bonded in a 4-coordinate geometry to one Mg(1), one Cr(2), and two equivalent Cr(1) atoms. In the second O site, O(2) is bonded to two equivalent Mg(2), one Cr(1), and two equivalent Cr(2) atoms to form distorted OMg2Cr3 trigonal bipyramids that share  a cornercorner with one O(3)Mg3Cr trigonal pyramid, corners with four equivalent O(4)Mg2Cr2 trigonal pyramids, edges with two equivalent O(2)Mg2Cr3 trigonal bipyramids,  an edgeedge with one O(4)Mg2Cr2 trigonal pyramid, and  an edgeedge with one O(3)Mg3Cr trigonal pyramid. In the third O site, O(3) is bonded to one Mg(2), two equivalent Mg(1), and one Cr(1) atom to form distorted OMg3Cr trigonal pyramids that share  a cornercorner with one O(2)Mg2Cr3 trigonal bipyramid, corners with two equivalent O(3)Mg3Cr trigonal pyramids, corners with three equivalent O(4)Mg2Cr2 trigonal pyramids, and  an edgeedge with one O(2)Mg2Cr3 trigonal bipyramid. In the fourth O site, O(4) is bonded to one Mg(1), one Mg(2), and two equivalent Cr(2) atoms to form OMg2Cr2 trigonal pyramids that share corners with four equivalent O(2)Mg2Cr3 trigonal bipyramids, corners with two equivalent O(4)Mg2Cr2 trigonal pyramids, corners with three equivalent O(3)Mg3Cr trigonal pyramids, and  an edgeedge with one O(2)Mg2Cr3 trigonal bipyramid.