Na3Mg2(WO4)3 crystallizes in the monoclinic C2/c space group. There are three inequivalent Na sites. In the first Na site, Na(1) is bonded in a 6-coordinate geometry to two equivalent O(2), two equivalent O(3), and two equivalent O(5) atoms. In the second Na site, Na(2) is bonded in a distorted hexagonal planar geometry to two equivalent O(4) and four equivalent O(3) atoms. In the third Na site, Na(3) is bonded to two equivalent O(5) and four equivalent O(6) atoms to form distorted NaO6 pentagonal pyramids that share corners with two equivalent Mg(1)O6 octahedra, corners with four equivalent W(2)O4 tetrahedra, edges with two equivalent Mg(1)O6 octahedra, edges with two equivalent Na(3)O6 pentagonal pyramids, and  an edgeedge with one W(1)O4 tetrahedra. The corner-sharing octahedral tilt angles are 67°. Mg(1) is bonded to one O(2), one O(4), one O(5), one O(6), and two equivalent O(1) atoms to form MgO6 octahedra that share  a cornercorner with one Na(3)O6 pentagonal pyramid, corners with two equivalent W(1)O4 tetrahedra, corners with four equivalent W(2)O4 tetrahedra,  an edgeedge with one Mg(1)O6 octahedra, and  an edgeedge with one Na(3)O6 pentagonal pyramid. There are two inequivalent W sites. In the first W site, W(1) is bonded to two equivalent O(4) and two equivalent O(5) atoms to form distorted WO4 tetrahedra that share corners with four equivalent Mg(1)O6 octahedra and  an edgeedge with one Na(3)O6 pentagonal pyramid. The corner-sharing octahedral tilt angles range from 60-65°. In the second W site, W(2) is bonded to one O(1), one O(2), one O(3), and one O(6) atom to form WO4 tetrahedra that share corners with four equivalent Mg(1)O6 octahedra and corners with two equivalent Na(3)O6 pentagonal pyramids. The corner-sharing octahedral tilt angles range from 39-64°. There are six inequivalent O sites. In the first O site, O(1) is bonded in a 3-coordinate geometry to two equivalent Mg(1) and one W(2) atom. In the second O site, O(2) is bonded in a distorted trigonal planar geometry to one Na(1), one Mg(1), and one W(2) atom. In the third O site, O(3) is bonded in a distorted rectangular see-saw-like geometry to one Na(1), two equivalent Na(2), and one W(2) atom. In the fourth O site, O(4) is bonded in a trigonal planar geometry to one Na(2), one Mg(1), and one W(1) atom. In the fifth O site, O(5) is bonded in a distorted see-saw-like geometry to one Na(1), one Na(3), one Mg(1), and one W(1) atom. In the sixth O site, O(6) is bonded to two equivalent Na(3), one Mg(1), and one W(2) atom to form a mixture of distorted edge and corner-sharing ONa2MgW trigonal pyramids.
Na3Mg2(WO4)3 crystallizes in the monoclinic C2/c space group. There are three inequivalent Na sites. In the first Na site, Na(1) is bonded in a 6-coordinate geometry to two equivalent O(2), two equivalent O(3), and two equivalent O(5) atoms. Both Na(1)-O(2) bond lengths are 2.34 Å. Both Na(1)-O(3) bond lengths are 2.45 Å. Both Na(1)-O(5) bond lengths are 2.44 Å. In the second Na site, Na(2) is bonded in a distorted hexagonal planar geometry to two equivalent O(4) and four equivalent O(3) atoms. Both Na(2)-O(4) bond lengths are 2.44 Å. There are two shorter (2.42 Å) and two longer (2.69 Å) Na(2)-O(3) bond lengths. In the third Na site, Na(3) is bonded to two equivalent O(5) and four equivalent O(6) atoms to form distorted NaO6 pentagonal pyramids that share corners with two equivalent Mg(1)O6 octahedra, corners with four equivalent W(2)O4 tetrahedra, edges with two equivalent Mg(1)O6 octahedra, edges with two equivalent Na(3)O6 pentagonal pyramids, and  an edgeedge with one W(1)O4 tetrahedra. The corner-sharing octahedral tilt angles are 67°. Both Na(3)-O(5) bond lengths are 2.64 Å. There are two shorter (2.50 Å) and two longer (2.59 Å) Na(3)-O(6) bond lengths. Mg(1) is bonded to one O(2), one O(4), one O(5), one O(6), and two equivalent O(1) atoms to form MgO6 octahedra that share  a cornercorner with one Na(3)O6 pentagonal pyramid, corners with two equivalent W(1)O4 tetrahedra, corners with four equivalent W(2)O4 tetrahedra,  an edgeedge with one Mg(1)O6 octahedra, and  an edgeedge with one Na(3)O6 pentagonal pyramid. The Mg(1)-O(2) bond length is 2.08 Å. The Mg(1)-O(4) bond length is 2.06 Å. The Mg(1)-O(5) bond length is 2.09 Å. The Mg(1)-O(6) bond length is 2.16 Å. There is one shorter (2.17 Å) and one longer (2.32 Å) Mg(1)-O(1) bond length. There are two inequivalent W sites. In the first W site, W(1) is bonded to two equivalent O(4) and two equivalent O(5) atoms to form distorted WO4 tetrahedra that share corners with four equivalent Mg(1)O6 octahedra and  an edgeedge with one Na(3)O6 pentagonal pyramid. The corner-sharing octahedral tilt angles range from 60-65°. Both W(1)-O(4) bond lengths are 1.88 Å. Both W(1)-O(5) bond lengths are 1.91 Å. In the second W site, W(2) is bonded to one O(1), one O(2), one O(3), and one O(6) atom to form WO4 tetrahedra that share corners with four equivalent Mg(1)O6 octahedra and corners with two equivalent Na(3)O6 pentagonal pyramids. The corner-sharing octahedral tilt angles range from 39-64°. The W(2)-O(1) bond length is 1.85 Å. The W(2)-O(2) bond length is 1.82 Å. The W(2)-O(3) bond length is 1.78 Å. The W(2)-O(6) bond length is 1.83 Å. There are six inequivalent O sites. In the first O site, O(1) is bonded in a 3-coordinate geometry to two equivalent Mg(1) and one W(2) atom. In the second O site, O(2) is bonded in a distorted trigonal planar geometry to one Na(1), one Mg(1), and one W(2) atom. In the third O site, O(3) is bonded in a distorted rectangular see-saw-like geometry to one Na(1), two equivalent Na(2), and one W(2) atom. In the fourth O site, O(4) is bonded in a trigonal planar geometry to one Na(2), one Mg(1), and one W(1) atom. In the fifth O site, O(5) is bonded in a distorted see-saw-like geometry to one Na(1), one Na(3), one Mg(1), and one W(1) atom. In the sixth O site, O(6) is bonded to two equivalent Na(3), one Mg(1), and one W(2) atom to form a mixture of distorted edge and corner-sharing ONa2MgW trigonal pyramids.