MgV4SnO12 crystallizes in the monoclinic C2 space group. Mg(1) is bonded to two equivalent O(2), two equivalent O(3), and two equivalent O(5) atoms to form distorted MgO6 octahedra that share corners with four equivalent V(2)O4 tetrahedra,  an edgeedge with one Sn(1)O6 octahedra, and edges with two equivalent V(1)O4 tetrahedra. There are two inequivalent V sites. In the first V site, V(1) is bonded to one O(1), one O(2), one O(4), and one O(5) atom to form VO4 tetrahedra that share  a cornercorner with one Sn(1)O6 octahedra, corners with two equivalent V(2)O4 tetrahedra, and  an edgeedge with one Mg(1)O6 octahedra. The corner-sharing octahedral tilt angles are 48°. In the second V site, V(2) is bonded to one O(3), one O(4), one O(5), and one O(6) atom to form VO4 tetrahedra that share corners with two equivalent Mg(1)O6 octahedra, corners with two equivalent Sn(1)O6 octahedra, and corners with two equivalent V(1)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 20-57°. Sn(1) is bonded to two equivalent O(1), two equivalent O(3), and two equivalent O(6) atoms to form SnO6 octahedra that share corners with two equivalent V(1)O4 tetrahedra, corners with four equivalent V(2)O4 tetrahedra, and  an edgeedge with one Mg(1)O6 octahedra. There are six inequivalent O sites. In the first O site, O(1) is bonded in a distorted bent 120 degrees geometry to one V(1) and one Sn(1) atom. In the second O site, O(2) is bonded in a water-like geometry to one Mg(1) and one V(1) atom. In the third O site, O(3) is bonded in a distorted trigonal planar geometry to one Mg(1), one V(2), and one Sn(1) atom. In the fourth O site, O(4) is bonded in a bent 150 degrees geometry to one V(1) and one V(2) atom. In the fifth O site, O(5) is bonded in a 3-coordinate geometry to one Mg(1), one V(1), and one V(2) atom. In the sixth O site, O(6) is bonded in a bent 150 degrees geometry to one V(2) and one Sn(1) atom.
MgV4SnO12 crystallizes in the monoclinic C2 space group. Mg(1) is bonded to two equivalent O(2), two equivalent O(3), and two equivalent O(5) atoms to form distorted MgO6 octahedra that share corners with four equivalent V(2)O4 tetrahedra,  an edgeedge with one Sn(1)O6 octahedra, and edges with two equivalent V(1)O4 tetrahedra. Both Mg(1)-O(2) bond lengths are 2.11 Å. Both Mg(1)-O(3) bond lengths are 2.08 Å. Both Mg(1)-O(5) bond lengths are 2.33 Å. There are two inequivalent V sites. In the first V site, V(1) is bonded to one O(1), one O(2), one O(4), and one O(5) atom to form VO4 tetrahedra that share  a cornercorner with one Sn(1)O6 octahedra, corners with two equivalent V(2)O4 tetrahedra, and  an edgeedge with one Mg(1)O6 octahedra. The corner-sharing octahedral tilt angles are 48°. The V(1)-O(1) bond length is 1.73 Å. The V(1)-O(2) bond length is 1.67 Å. The V(1)-O(4) bond length is 1.76 Å. The V(1)-O(5) bond length is 1.83 Å. In the second V site, V(2) is bonded to one O(3), one O(4), one O(5), and one O(6) atom to form VO4 tetrahedra that share corners with two equivalent Mg(1)O6 octahedra, corners with two equivalent Sn(1)O6 octahedra, and corners with two equivalent V(1)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 20-57°. The V(2)-O(3) bond length is 1.81 Å. The V(2)-O(4) bond length is 1.85 Å. The V(2)-O(5) bond length is 1.89 Å. The V(2)-O(6) bond length is 1.74 Å. Sn(1) is bonded to two equivalent O(1), two equivalent O(3), and two equivalent O(6) atoms to form SnO6 octahedra that share corners with two equivalent V(1)O4 tetrahedra, corners with four equivalent V(2)O4 tetrahedra, and  an edgeedge with one Mg(1)O6 octahedra. Both Sn(1)-O(1) bond lengths are 2.07 Å. Both Sn(1)-O(3) bond lengths are 2.13 Å. Both Sn(1)-O(6) bond lengths are 2.07 Å. There are six inequivalent O sites. In the first O site, O(1) is bonded in a distorted bent 120 degrees geometry to one V(1) and one Sn(1) atom. In the second O site, O(2) is bonded in a water-like geometry to one Mg(1) and one V(1) atom. In the third O site, O(3) is bonded in a distorted trigonal planar geometry to one Mg(1), one V(2), and one Sn(1) atom. In the fourth O site, O(4) is bonded in a bent 150 degrees geometry to one V(1) and one V(2) atom. In the fifth O site, O(5) is bonded in a 3-coordinate geometry to one Mg(1), one V(1), and one V(2) atom. In the sixth O site, O(6) is bonded in a bent 150 degrees geometry to one V(2) and one Sn(1) atom.