MgV3SnO8 crystallizes in the monoclinic Cm space group. Mg(1) is bonded to one O(1), one O(2), one O(3), and two equivalent O(6) atoms to form MgO5 trigonal bipyramids that share corners with two equivalent Mg(1)O5 trigonal bipyramids,  an edgeedge with one V(1)O6 octahedra, edges with two equivalent V(2)O6 octahedra, and edges with two equivalent Sn(1)O6 octahedra. There are three inequivalent V sites. In the first V site, V(1) is bonded to one O(2), one O(3), one O(4), one O(5), and two equivalent O(8) atoms to form VO6 octahedra that share  a cornercorner with one Sn(1)O6 octahedra, corners with two equivalent V(1)O6 octahedra,  an edgeedge with one V(2)O6 octahedra, edges with two equivalent Sn(1)O6 octahedra, and  an edgeedge with one Mg(1)O5 trigonal bipyramid. The corner-sharing octahedral tilt angles range from 25-27°. In the second V site, V(2) is bonded to one O(4), one O(5), one O(6), one O(7), and two equivalent O(1) atoms to form VO6 octahedra that share  a cornercorner with one Sn(1)O6 octahedra, corners with two equivalent V(2)O6 octahedra,  an edgeedge with one V(1)O6 octahedra,  an edgeedge with one Sn(1)O6 octahedra, and edges with two equivalent Mg(1)O5 trigonal bipyramids. The corner-sharing octahedral tilt angles range from 8-33°. In the third V site, V(3) is bonded in a 5-coordinate geometry to one O(1), one O(3), one O(4), and two equivalent O(7) atoms. Sn(1) is bonded to one O(5), one O(6), one O(7), one O(8), and two equivalent O(2) atoms to form SnO6 octahedra that share  a cornercorner with one V(1)O6 octahedra,  a cornercorner with one V(2)O6 octahedra, corners with two equivalent Sn(1)O6 octahedra,  an edgeedge with one V(2)O6 octahedra, edges with two equivalent V(1)O6 octahedra, and edges with two equivalent Mg(1)O5 trigonal bipyramids. The corner-sharing octahedral tilt angles range from 8-27°. There are eight inequivalent O sites. In the first O site, O(1) is bonded to one Mg(1), one V(3), and two equivalent V(2) atoms to form OMgV3 trigonal pyramids that share  a cornercorner with one O(2)MgVSn2 trigonal pyramid, corners with two equivalent O(1)MgV3 trigonal pyramids, and edges with two equivalent O(7)V3Sn trigonal pyramids. In the second O site, O(2) is bonded to one Mg(1), one V(1), and two equivalent Sn(1) atoms to form OMgVSn2 trigonal pyramids that share  a cornercorner with one O(1)MgV3 trigonal pyramid, corners with two equivalent O(2)MgVSn2 trigonal pyramids, and corners with two equivalent O(7)V3Sn trigonal pyramids. In the third O site, O(3) is bonded in a T-shaped geometry to one Mg(1), one V(1), and one V(3) atom. In the fourth O site, O(4) is bonded in a distorted trigonal planar geometry to one V(1), one V(2), and one V(3) atom. In the fifth O site, O(5) is bonded in a distorted T-shaped geometry to one V(1), one V(2), and one Sn(1) atom. In the sixth O site, O(6) is bonded in a rectangular see-saw-like geometry to two equivalent Mg(1), one V(2), and one Sn(1) atom. In the seventh O site, O(7) is bonded to one V(2), two equivalent V(3), and one Sn(1) atom to form OV3Sn trigonal pyramids that share corners with two equivalent O(2)MgVSn2 trigonal pyramids, corners with two equivalent O(7)V3Sn trigonal pyramids, and edges with two equivalent O(1)MgV3 trigonal pyramids. In the eighth O site, O(8) is bonded in a distorted T-shaped geometry to two equivalent V(1) and one Sn(1) atom.
MgV3SnO8 crystallizes in the monoclinic Cm space group. Mg(1) is bonded to one O(1), one O(2), one O(3), and two equivalent O(6) atoms to form MgO5 trigonal bipyramids that share corners with two equivalent Mg(1)O5 trigonal bipyramids,  an edgeedge with one V(1)O6 octahedra, edges with two equivalent V(2)O6 octahedra, and edges with two equivalent Sn(1)O6 octahedra. The Mg(1)-O(1) bond length is 1.97 Å. The Mg(1)-O(2) bond length is 2.04 Å. The Mg(1)-O(3) bond length is 2.21 Å. Both Mg(1)-O(6) bond lengths are 2.03 Å. There are three inequivalent V sites. In the first V site, V(1) is bonded to one O(2), one O(3), one O(4), one O(5), and two equivalent O(8) atoms to form VO6 octahedra that share  a cornercorner with one Sn(1)O6 octahedra, corners with two equivalent V(1)O6 octahedra,  an edgeedge with one V(2)O6 octahedra, edges with two equivalent Sn(1)O6 octahedra, and  an edgeedge with one Mg(1)O5 trigonal bipyramid. The corner-sharing octahedral tilt angles range from 25-27°. The V(1)-O(2) bond length is 2.13 Å. The V(1)-O(3) bond length is 2.23 Å. The V(1)-O(4) bond length is 2.08 Å. The V(1)-O(5) bond length is 1.93 Å. Both V(1)-O(8) bond lengths are 2.03 Å. In the second V site, V(2) is bonded to one O(4), one O(5), one O(6), one O(7), and two equivalent O(1) atoms to form VO6 octahedra that share  a cornercorner with one Sn(1)O6 octahedra, corners with two equivalent V(2)O6 octahedra,  an edgeedge with one V(1)O6 octahedra,  an edgeedge with one Sn(1)O6 octahedra, and edges with two equivalent Mg(1)O5 trigonal bipyramids. The corner-sharing octahedral tilt angles range from 8-33°. The V(2)-O(4) bond length is 1.99 Å. The V(2)-O(5) bond length is 2.00 Å. The V(2)-O(6) bond length is 2.23 Å. The V(2)-O(7) bond length is 2.21 Å. Both V(2)-O(1) bond lengths are 2.06 Å. In the third V site, V(3) is bonded in a 5-coordinate geometry to one O(1), one O(3), one O(4), and two equivalent O(7) atoms. The V(3)-O(1) bond length is 2.04 Å. The V(3)-O(3) bond length is 1.71 Å. The V(3)-O(4) bond length is 1.93 Å. Both V(3)-O(7) bond lengths are 2.10 Å. Sn(1) is bonded to one O(5), one O(6), one O(7), one O(8), and two equivalent O(2) atoms to form SnO6 octahedra that share  a cornercorner with one V(1)O6 octahedra,  a cornercorner with one V(2)O6 octahedra, corners with two equivalent Sn(1)O6 octahedra,  an edgeedge with one V(2)O6 octahedra, edges with two equivalent V(1)O6 octahedra, and edges with two equivalent Mg(1)O5 trigonal bipyramids. The corner-sharing octahedral tilt angles range from 8-27°. The Sn(1)-O(5) bond length is 1.98 Å. The Sn(1)-O(6) bond length is 2.15 Å. The Sn(1)-O(7) bond length is 2.21 Å. The Sn(1)-O(8) bond length is 2.08 Å. Both Sn(1)-O(2) bond lengths are 2.02 Å. There are eight inequivalent O sites. In the first O site, O(1) is bonded to one Mg(1), one V(3), and two equivalent V(2) atoms to form OMgV3 trigonal pyramids that share  a cornercorner with one O(2)MgVSn2 trigonal pyramid, corners with two equivalent O(1)MgV3 trigonal pyramids, and edges with two equivalent O(7)V3Sn trigonal pyramids. In the second O site, O(2) is bonded to one Mg(1), one V(1), and two equivalent Sn(1) atoms to form OMgVSn2 trigonal pyramids that share  a cornercorner with one O(1)MgV3 trigonal pyramid, corners with two equivalent O(2)MgVSn2 trigonal pyramids, and corners with two equivalent O(7)V3Sn trigonal pyramids. In the third O site, O(3) is bonded in a T-shaped geometry to one Mg(1), one V(1), and one V(3) atom. In the fourth O site, O(4) is bonded in a distorted trigonal planar geometry to one V(1), one V(2), and one V(3) atom. In the fifth O site, O(5) is bonded in a distorted T-shaped geometry to one V(1), one V(2), and one Sn(1) atom. In the sixth O site, O(6) is bonded in a rectangular see-saw-like geometry to two equivalent Mg(1), one V(2), and one Sn(1) atom. In the seventh O site, O(7) is bonded to one V(2), two equivalent V(3), and one Sn(1) atom to form OV3Sn trigonal pyramids that share corners with two equivalent O(2)MgVSn2 trigonal pyramids, corners with two equivalent O(7)V3Sn trigonal pyramids, and edges with two equivalent O(1)MgV3 trigonal pyramids. In the eighth O site, O(8) is bonded in a distorted T-shaped geometry to two equivalent V(1) and one Sn(1) atom.