MgV2(FeO4)2 crystallizes in the monoclinic Pm space group. Mg(1) is bonded to one O(2), one O(3), and two equivalent O(5) atoms to form distorted MgO4 tetrahedra that share corners with six equivalent Fe(1)O6 octahedra, corners with two equivalent V(2)O4 tetrahedra, and  an edgeedge with one V(1)O4 tetrahedra. The corner-sharing octahedral tilt angles are 68°. There are two inequivalent V sites. In the first V site, V(1) is bonded to one O(2), one O(3), and two equivalent O(6) atoms to form VO4 tetrahedra that share corners with six equivalent Fe(1)O6 octahedra and  an edgeedge with one Mg(1)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 44-57°. In the second V site, V(2) is bonded to one O(1), one O(4), and two equivalent O(5) atoms to form VO4 tetrahedra that share corners with six equivalent Fe(1)O6 octahedra and corners with two equivalent Mg(1)O4 tetrahedra. The corner-sharing octahedral tilt angles are 53°. Fe(1) is bonded to one O(1), one O(2), one O(3), one O(4), one O(5), and one O(6) atom to form FeO6 octahedra that share corners with three equivalent Mg(1)O4 tetrahedra, corners with three equivalent V(1)O4 tetrahedra, corners with three equivalent V(2)O4 tetrahedra, and edges with two equivalent Fe(1)O6 octahedra. There are six inequivalent O sites. In the first O site, O(1) is bonded in a distorted trigonal planar geometry to one V(2) and two equivalent Fe(1) atoms. In the second O site, O(2) is bonded to one Mg(1), one V(1), and two equivalent Fe(1) atoms to form distorted edge-sharing OMgVFe2 tetrahedra. In the third O site, O(3) is bonded to one Mg(1), one V(1), and two equivalent Fe(1) atoms to form distorted edge-sharing OMgVFe2 tetrahedra. In the fourth O site, O(4) is bonded in a distorted trigonal planar geometry to one V(2) and two equivalent Fe(1) atoms. In the fifth O site, O(5) is bonded in a trigonal planar geometry to one Mg(1), one V(2), and one Fe(1) atom. In the sixth O site, O(6) is bonded in a distorted bent 150 degrees geometry to one V(1) and one Fe(1) atom.
MgV2(FeO4)2 crystallizes in the monoclinic Pm space group. Mg(1) is bonded to one O(2), one O(3), and two equivalent O(5) atoms to form distorted MgO4 tetrahedra that share corners with six equivalent Fe(1)O6 octahedra, corners with two equivalent V(2)O4 tetrahedra, and  an edgeedge with one V(1)O4 tetrahedra. The corner-sharing octahedral tilt angles are 68°. The Mg(1)-O(2) bond length is 2.10 Å. The Mg(1)-O(3) bond length is 2.10 Å. Both Mg(1)-O(5) bond lengths are 1.97 Å. There are two inequivalent V sites. In the first V site, V(1) is bonded to one O(2), one O(3), and two equivalent O(6) atoms to form VO4 tetrahedra that share corners with six equivalent Fe(1)O6 octahedra and  an edgeedge with one Mg(1)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 44-57°. The V(1)-O(2) bond length is 1.83 Å. The V(1)-O(3) bond length is 1.84 Å. Both V(1)-O(6) bond lengths are 1.68 Å. In the second V site, V(2) is bonded to one O(1), one O(4), and two equivalent O(5) atoms to form VO4 tetrahedra that share corners with six equivalent Fe(1)O6 octahedra and corners with two equivalent Mg(1)O4 tetrahedra. The corner-sharing octahedral tilt angles are 53°. The V(2)-O(1) bond length is 1.75 Å. The V(2)-O(4) bond length is 1.76 Å. Both V(2)-O(5) bond lengths are 1.76 Å. Fe(1) is bonded to one O(1), one O(2), one O(3), one O(4), one O(5), and one O(6) atom to form FeO6 octahedra that share corners with three equivalent Mg(1)O4 tetrahedra, corners with three equivalent V(1)O4 tetrahedra, corners with three equivalent V(2)O4 tetrahedra, and edges with two equivalent Fe(1)O6 octahedra. The Fe(1)-O(1) bond length is 2.15 Å. The Fe(1)-O(2) bond length is 2.22 Å. The Fe(1)-O(3) bond length is 2.21 Å. The Fe(1)-O(4) bond length is 2.14 Å. The Fe(1)-O(5) bond length is 2.22 Å. The Fe(1)-O(6) bond length is 2.10 Å. There are six inequivalent O sites. In the first O site, O(1) is bonded in a distorted trigonal planar geometry to one V(2) and two equivalent Fe(1) atoms. In the second O site, O(2) is bonded to one Mg(1), one V(1), and two equivalent Fe(1) atoms to form distorted edge-sharing OMgVFe2 tetrahedra. In the third O site, O(3) is bonded to one Mg(1), one V(1), and two equivalent Fe(1) atoms to form distorted edge-sharing OMgVFe2 tetrahedra. In the fourth O site, O(4) is bonded in a distorted trigonal planar geometry to one V(2) and two equivalent Fe(1) atoms. In the fifth O site, O(5) is bonded in a trigonal planar geometry to one Mg(1), one V(2), and one Fe(1) atom. In the sixth O site, O(6) is bonded in a distorted bent 150 degrees geometry to one V(1) and one Fe(1) atom.