MgV2Cr4O12 crystallizes in the monoclinic Pm space group. Mg(1) is bonded to one O(3), one O(5), two equivalent O(1), and two equivalent O(7) atoms to form MgO6 octahedra that share corners with four equivalent Cr(1)O6 octahedra, edges with four equivalent Cr(2)O6 octahedra, and faces with two equivalent V(1)O6 octahedra. The corner-sharing octahedral tilt angles are 46°. There are two inequivalent V sites. In the first V site, V(1) is bonded to one O(3), one O(5), two equivalent O(1), and two equivalent O(7) atoms to form VO6 octahedra that share corners with eight equivalent Cr(2)O6 octahedra, edges with two equivalent Cr(1)O6 octahedra, and faces with two equivalent Mg(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 45-50°. In the second V site, V(2) is bonded to one O(2), one O(8), two equivalent O(4), and two equivalent O(6) atoms to form distorted VO6 octahedra that share corners with eight equivalent Cr(1)O6 octahedra and edges with two equivalent Cr(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 44-50°. There are two inequivalent Cr sites. In the first Cr site, Cr(1) is bonded to one O(1), one O(2), one O(4), one O(6), one O(7), and one O(8) atom to form CrO6 octahedra that share corners with two equivalent Mg(1)O6 octahedra, corners with four equivalent V(2)O6 octahedra, corners with four equivalent Cr(2)O6 octahedra,  an edgeedge with one V(1)O6 octahedra, and  an edgeedge with one Cr(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 44-54°. In the second Cr site, Cr(2) is bonded to one O(1), one O(3), one O(4), one O(5), one O(6), and one O(7) atom to form CrO6 octahedra that share corners with four equivalent V(1)O6 octahedra, corners with four equivalent Cr(1)O6 octahedra,  an edgeedge with one V(2)O6 octahedra,  an edgeedge with one Cr(2)O6 octahedra, and edges with two equivalent Mg(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 45-54°. There are eight inequivalent O sites. In the first O site, O(1) is bonded in a rectangular see-saw-like geometry to one Mg(1), one V(1), one Cr(1), and one Cr(2) atom. In the second O site, O(2) is bonded in a distorted T-shaped geometry to one V(2) and two equivalent Cr(1) atoms. In the third O site, O(3) is bonded to one Mg(1), one V(1), and two equivalent Cr(2) atoms to form a mixture of edge and corner-sharing OMgVCr2 trigonal pyramids. In the fourth O site, O(4) is bonded in a distorted trigonal planar geometry to one V(2), one Cr(1), and one Cr(2) atom. In the fifth O site, O(5) is bonded to one Mg(1), one V(1), and two equivalent Cr(2) atoms to form a mixture of edge and corner-sharing OMgVCr2 trigonal pyramids. In the sixth O site, O(6) is bonded in a distorted trigonal planar geometry to one V(2), one Cr(1), and one Cr(2) atom. In the seventh O site, O(7) is bonded in a rectangular see-saw-like geometry to one Mg(1), one V(1), one Cr(1), and one Cr(2) atom. In the eighth O site, O(8) is bonded in a 3-coordinate geometry to one V(2) and two equivalent Cr(1) atoms.
MgV2Cr4O12 crystallizes in the monoclinic Pm space group. Mg(1) is bonded to one O(3), one O(5), two equivalent O(1), and two equivalent O(7) atoms to form MgO6 octahedra that share corners with four equivalent Cr(1)O6 octahedra, edges with four equivalent Cr(2)O6 octahedra, and faces with two equivalent V(1)O6 octahedra. The corner-sharing octahedral tilt angles are 46°. The Mg(1)-O(3) bond length is 1.90 Å. The Mg(1)-O(5) bond length is 1.91 Å. Both Mg(1)-O(1) bond lengths are 2.09 Å. Both Mg(1)-O(7) bond lengths are 2.10 Å. There are two inequivalent V sites. In the first V site, V(1) is bonded to one O(3), one O(5), two equivalent O(1), and two equivalent O(7) atoms to form VO6 octahedra that share corners with eight equivalent Cr(2)O6 octahedra, edges with two equivalent Cr(1)O6 octahedra, and faces with two equivalent Mg(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 45-50°. The V(1)-O(3) bond length is 2.00 Å. The V(1)-O(5) bond length is 2.00 Å. Both V(1)-O(1) bond lengths are 1.96 Å. Both V(1)-O(7) bond lengths are 1.95 Å. In the second V site, V(2) is bonded to one O(2), one O(8), two equivalent O(4), and two equivalent O(6) atoms to form distorted VO6 octahedra that share corners with eight equivalent Cr(1)O6 octahedra and edges with two equivalent Cr(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 44-50°. The V(2)-O(2) bond length is 1.81 Å. The V(2)-O(8) bond length is 2.43 Å. Both V(2)-O(4) bond lengths are 1.88 Å. Both V(2)-O(6) bond lengths are 1.87 Å. There are two inequivalent Cr sites. In the first Cr site, Cr(1) is bonded to one O(1), one O(2), one O(4), one O(6), one O(7), and one O(8) atom to form CrO6 octahedra that share corners with two equivalent Mg(1)O6 octahedra, corners with four equivalent V(2)O6 octahedra, corners with four equivalent Cr(2)O6 octahedra,  an edgeedge with one V(1)O6 octahedra, and  an edgeedge with one Cr(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 44-54°. The Cr(1)-O(1) bond length is 2.04 Å. The Cr(1)-O(2) bond length is 2.01 Å. The Cr(1)-O(4) bond length is 2.04 Å. The Cr(1)-O(6) bond length is 2.05 Å. The Cr(1)-O(7) bond length is 2.03 Å. The Cr(1)-O(8) bond length is 1.90 Å. In the second Cr site, Cr(2) is bonded to one O(1), one O(3), one O(4), one O(5), one O(6), and one O(7) atom to form CrO6 octahedra that share corners with four equivalent V(1)O6 octahedra, corners with four equivalent Cr(1)O6 octahedra,  an edgeedge with one V(2)O6 octahedra,  an edgeedge with one Cr(2)O6 octahedra, and edges with two equivalent Mg(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 45-54°. The Cr(2)-O(1) bond length is 2.12 Å. The Cr(2)-O(3) bond length is 2.04 Å. The Cr(2)-O(4) bond length is 1.98 Å. The Cr(2)-O(5) bond length is 2.04 Å. The Cr(2)-O(6) bond length is 1.98 Å. The Cr(2)-O(7) bond length is 2.08 Å. There are eight inequivalent O sites. In the first O site, O(1) is bonded in a rectangular see-saw-like geometry to one Mg(1), one V(1), one Cr(1), and one Cr(2) atom. In the second O site, O(2) is bonded in a distorted T-shaped geometry to one V(2) and two equivalent Cr(1) atoms. In the third O site, O(3) is bonded to one Mg(1), one V(1), and two equivalent Cr(2) atoms to form a mixture of edge and corner-sharing OMgVCr2 trigonal pyramids. In the fourth O site, O(4) is bonded in a distorted trigonal planar geometry to one V(2), one Cr(1), and one Cr(2) atom. In the fifth O site, O(5) is bonded to one Mg(1), one V(1), and two equivalent Cr(2) atoms to form a mixture of edge and corner-sharing OMgVCr2 trigonal pyramids. In the sixth O site, O(6) is bonded in a distorted trigonal planar geometry to one V(2), one Cr(1), and one Cr(2) atom. In the seventh O site, O(7) is bonded in a rectangular see-saw-like geometry to one Mg(1), one V(1), one Cr(1), and one Cr(2) atom. In the eighth O site, O(8) is bonded in a 3-coordinate geometry to one V(2) and two equivalent Cr(1) atoms.