Mg(W2O3)2 crystallizes in the orthorhombic Cmcm space group. Mg(1) is bonded in a distorted see-saw-like geometry to two equivalent O(3) and two equivalent O(4) atoms. There are two inequivalent W sites. In the first W site, W(1) is bonded to one O(2), two equivalent O(1), and two equivalent O(3) atoms to form a mixture of corner and edge-sharing WO5 square pyramids. In the second W site, W(2) is bonded in a 6-coordinate geometry to one O(1), one O(4), two equivalent O(2), and two equivalent O(3) atoms. There are four inequivalent O sites. In the first O site, O(1) is bonded to two equivalent W(2) and four equivalent W(1) atoms to form OW6 octahedra that share corners with two equivalent O(4)Mg2W2 tetrahedra, corners with eight equivalent O(3)MgW4 trigonal bipyramids, edges with two equivalent O(1)W6 octahedra, and edges with two equivalent O(3)MgW4 trigonal bipyramids. In the second O site, O(2) is bonded in a trigonal non-coplanar geometry to one W(1) and two equivalent W(2) atoms. In the third O site, O(3) is bonded to one Mg(1), two equivalent W(1), and two equivalent W(2) atoms to form distorted OMgW4 trigonal bipyramids that share corners with four equivalent O(1)W6 octahedra,  a cornercorner with one O(3)MgW4 trigonal bipyramid,  an edgeedge with one O(1)W6 octahedra, edges with two equivalent O(4)Mg2W2 tetrahedra, and edges with two equivalent O(3)MgW4 trigonal bipyramids. The corner-sharing octahedral tilt angles range from 13-73°. In the fourth O site, O(4) is bonded to two equivalent Mg(1) and two equivalent W(2) atoms to form OMg2W2 tetrahedra that share corners with two equivalent O(1)W6 octahedra, corners with two equivalent O(4)Mg2W2 tetrahedra, and edges with four equivalent O(3)MgW4 trigonal bipyramids. The corner-sharing octahedral tilt angles are 3°.
Mg(W2O3)2 crystallizes in the orthorhombic Cmcm space group. Mg(1) is bonded in a distorted see-saw-like geometry to two equivalent O(3) and two equivalent O(4) atoms. Both Mg(1)-O(3) bond lengths are 2.13 Å. Both Mg(1)-O(4) bond lengths are 2.02 Å. There are two inequivalent W sites. In the first W site, W(1) is bonded to one O(2), two equivalent O(1), and two equivalent O(3) atoms to form a mixture of corner and edge-sharing WO5 square pyramids. The W(1)-O(2) bond length is 2.16 Å. Both W(1)-O(1) bond lengths are 2.31 Å. Both W(1)-O(3) bond lengths are 2.26 Å. In the second W site, W(2) is bonded in a 6-coordinate geometry to one O(1), one O(4), two equivalent O(2), and two equivalent O(3) atoms. The W(2)-O(1) bond length is 2.67 Å. The W(2)-O(4) bond length is 2.11 Å. Both W(2)-O(2) bond lengths are 2.13 Å. Both W(2)-O(3) bond lengths are 2.33 Å. There are four inequivalent O sites. In the first O site, O(1) is bonded to two equivalent W(2) and four equivalent W(1) atoms to form OW6 octahedra that share corners with two equivalent O(4)Mg2W2 tetrahedra, corners with eight equivalent O(3)MgW4 trigonal bipyramids, edges with two equivalent O(1)W6 octahedra, and edges with two equivalent O(3)MgW4 trigonal bipyramids. In the second O site, O(2) is bonded in a trigonal non-coplanar geometry to one W(1) and two equivalent W(2) atoms. In the third O site, O(3) is bonded to one Mg(1), two equivalent W(1), and two equivalent W(2) atoms to form distorted OMgW4 trigonal bipyramids that share corners with four equivalent O(1)W6 octahedra,  a cornercorner with one O(3)MgW4 trigonal bipyramid,  an edgeedge with one O(1)W6 octahedra, edges with two equivalent O(4)Mg2W2 tetrahedra, and edges with two equivalent O(3)MgW4 trigonal bipyramids. The corner-sharing octahedral tilt angles range from 13-73°. In the fourth O site, O(4) is bonded to two equivalent Mg(1) and two equivalent W(2) atoms to form OMg2W2 tetrahedra that share corners with two equivalent O(1)W6 octahedra, corners with two equivalent O(4)Mg2W2 tetrahedra, and edges with four equivalent O(3)MgW4 trigonal bipyramids. The corner-sharing octahedral tilt angles are 3°.