Na4Mg(MoO4)2 crystallizes in the orthorhombic Imm2 space group. There are two inequivalent Na sites. In the first Na site, Na(1) is bonded in a 5-coordinate geometry to one O(1), two equivalent O(2), and two equivalent O(4) atoms. In the second Na site, Na(2) is bonded to one O(2), one O(4), two equivalent O(1), and two equivalent O(3) atoms to form distorted NaO6 octahedra that share corners with three equivalent Mg(1)O4 tetrahedra, corners with three equivalent Mo(1)O4 tetrahedra, corners with three equivalent Mo(2)O4 tetrahedra, and edges with two equivalent Na(2)O6 octahedra. Mg(1) is bonded to two equivalent O(3) and two equivalent O(4) atoms to form distorted MgO4 tetrahedra that share corners with six equivalent Na(2)O6 octahedra, corners with two equivalent Mo(2)O4 tetrahedra, and  an edgeedge with one Mo(1)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 43-67°. There are two inequivalent Mo sites. In the first Mo site, Mo(1) is bonded to two equivalent O(2) and two equivalent O(3) atoms to form distorted MoO4 tetrahedra that share corners with six equivalent Na(2)O6 octahedra and  an edgeedge with one Mg(1)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 46-65°. In the second Mo site, Mo(2) is bonded to two equivalent O(1) and two equivalent O(4) atoms to form MoO4 tetrahedra that share corners with six equivalent Na(2)O6 octahedra and corners with two equivalent Mg(1)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 46-71°. There are four inequivalent O sites. In the first O site, O(1) is bonded in a distorted rectangular see-saw-like geometry to one Na(1), two equivalent Na(2), and one Mo(2) atom. In the second O site, O(2) is bonded to one Na(2), two equivalent Na(1), and one Mo(1) atom to form a mixture of corner and edge-sharing ONa3Mo tetrahedra. In the third O site, O(3) is bonded in a rectangular see-saw-like geometry to two equivalent Na(2), one Mg(1), and one Mo(1) atom. In the fourth O site, O(4) is bonded in a 5-coordinate geometry to one Na(2), two equivalent Na(1), one Mg(1), and one Mo(2) atom.
Na4Mg(MoO4)2 crystallizes in the orthorhombic Imm2 space group. There are two inequivalent Na sites. In the first Na site, Na(1) is bonded in a 5-coordinate geometry to one O(1), two equivalent O(2), and two equivalent O(4) atoms. The Na(1)-O(1) bond length is 2.30 Å. Both Na(1)-O(2) bond lengths are 2.28 Å. Both Na(1)-O(4) bond lengths are 2.52 Å. In the second Na site, Na(2) is bonded to one O(2), one O(4), two equivalent O(1), and two equivalent O(3) atoms to form distorted NaO6 octahedra that share corners with three equivalent Mg(1)O4 tetrahedra, corners with three equivalent Mo(1)O4 tetrahedra, corners with three equivalent Mo(2)O4 tetrahedra, and edges with two equivalent Na(2)O6 octahedra. The Na(2)-O(2) bond length is 2.32 Å. The Na(2)-O(4) bond length is 2.70 Å. Both Na(2)-O(1) bond lengths are 2.52 Å. Both Na(2)-O(3) bond lengths are 2.50 Å. Mg(1) is bonded to two equivalent O(3) and two equivalent O(4) atoms to form distorted MgO4 tetrahedra that share corners with six equivalent Na(2)O6 octahedra, corners with two equivalent Mo(2)O4 tetrahedra, and  an edgeedge with one Mo(1)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 43-67°. Both Mg(1)-O(3) bond lengths are 1.98 Å. Both Mg(1)-O(4) bond lengths are 2.00 Å. There are two inequivalent Mo sites. In the first Mo site, Mo(1) is bonded to two equivalent O(2) and two equivalent O(3) atoms to form distorted MoO4 tetrahedra that share corners with six equivalent Na(2)O6 octahedra and  an edgeedge with one Mg(1)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 46-65°. Both Mo(1)-O(2) bond lengths are 1.83 Å. Both Mo(1)-O(3) bond lengths are 1.95 Å. In the second Mo site, Mo(2) is bonded to two equivalent O(1) and two equivalent O(4) atoms to form MoO4 tetrahedra that share corners with six equivalent Na(2)O6 octahedra and corners with two equivalent Mg(1)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 46-71°. Both Mo(2)-O(1) bond lengths are 1.84 Å. Both Mo(2)-O(4) bond lengths are 1.92 Å. There are four inequivalent O sites. In the first O site, O(1) is bonded in a distorted rectangular see-saw-like geometry to one Na(1), two equivalent Na(2), and one Mo(2) atom. In the second O site, O(2) is bonded to one Na(2), two equivalent Na(1), and one Mo(1) atom to form a mixture of corner and edge-sharing ONa3Mo tetrahedra. In the third O site, O(3) is bonded in a rectangular see-saw-like geometry to two equivalent Na(2), one Mg(1), and one Mo(1) atom. In the fourth O site, O(4) is bonded in a 5-coordinate geometry to one Na(2), two equivalent Na(1), one Mg(1), and one Mo(2) atom.