Na3MgCu2SbO6 crystallizes in the monoclinic Cm space group. There are two inequivalent Na sites. In the first Na site, Na(1) is bonded in a distorted rectangular see-saw-like geometry to one O(1), one O(2), one O(3), and one O(4) atom. In the second Na site, Na(2) is bonded to one O(2), one O(3), two equivalent O(1), and two equivalent O(4) atoms to form distorted NaO6 octahedra that share corners with two equivalent Sb(1)O6 octahedra, edges with two equivalent Sb(1)O6 octahedra, and faces with two equivalent Mg(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 10-11°. Mg(1) is bonded to one O(2), one O(3), two equivalent O(1), and two equivalent O(4) atoms to form distorted MgO6 octahedra that share faces with two equivalent Na(2)O6 octahedra and faces with two equivalent Sb(1)O6 octahedra. Cu(1) is bonded in a linear geometry to one O(1) and one O(4) atom. Sb(1) is bonded to one O(2), one O(3), two equivalent O(1), and two equivalent O(4) atoms to form SbO6 octahedra that share corners with two equivalent Na(2)O6 octahedra, edges with two equivalent Na(2)O6 octahedra, and faces with two equivalent Mg(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 10-11°. There are four inequivalent O sites. In the first O site, O(1) is bonded in a 5-coordinate geometry to one Na(1), one Na(2), one Mg(1), one Cu(1), and one Sb(1) atom. In the second O site, O(2) is bonded to one Na(2), two equivalent Na(1), one Mg(1), and one Sb(1) atom to form a mixture of corner and edge-sharing ONa3MgSb trigonal bipyramids. In the third O site, O(3) is bonded to one Na(2), two equivalent Na(1), one Mg(1), and one Sb(1) atom to form a mixture of corner and edge-sharing ONa3MgSb trigonal bipyramids. In the fourth O site, O(4) is bonded in a 5-coordinate geometry to one Na(1), one Na(2), one Mg(1), one Cu(1), and one Sb(1) atom.
Na3MgCu2SbO6 crystallizes in the monoclinic Cm space group. There are two inequivalent Na sites. In the first Na site, Na(1) is bonded in a distorted rectangular see-saw-like geometry to one O(1), one O(2), one O(3), and one O(4) atom. The Na(1)-O(1) bond length is 2.50 Å. The Na(1)-O(2) bond length is 2.34 Å. The Na(1)-O(3) bond length is 2.34 Å. The Na(1)-O(4) bond length is 2.48 Å. In the second Na site, Na(2) is bonded to one O(2), one O(3), two equivalent O(1), and two equivalent O(4) atoms to form distorted NaO6 octahedra that share corners with two equivalent Sb(1)O6 octahedra, edges with two equivalent Sb(1)O6 octahedra, and faces with two equivalent Mg(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 10-11°. The Na(2)-O(2) bond length is 2.29 Å. The Na(2)-O(3) bond length is 2.28 Å. Both Na(2)-O(1) bond lengths are 2.50 Å. Both Na(2)-O(4) bond lengths are 2.55 Å. Mg(1) is bonded to one O(2), one O(3), two equivalent O(1), and two equivalent O(4) atoms to form distorted MgO6 octahedra that share faces with two equivalent Na(2)O6 octahedra and faces with two equivalent Sb(1)O6 octahedra. The Mg(1)-O(2) bond length is 2.02 Å. The Mg(1)-O(3) bond length is 2.03 Å. Both Mg(1)-O(1) bond lengths are 2.29 Å. Both Mg(1)-O(4) bond lengths are 2.24 Å. Cu(1) is bonded in a linear geometry to one O(1) and one O(4) atom. The Cu(1)-O(1) bond length is 1.86 Å. The Cu(1)-O(4) bond length is 1.86 Å. Sb(1) is bonded to one O(2), one O(3), two equivalent O(1), and two equivalent O(4) atoms to form SbO6 octahedra that share corners with two equivalent Na(2)O6 octahedra, edges with two equivalent Na(2)O6 octahedra, and faces with two equivalent Mg(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 10-11°. The Sb(1)-O(2) bond length is 1.99 Å. The Sb(1)-O(3) bond length is 1.99 Å. Both Sb(1)-O(1) bond lengths are 2.06 Å. Both Sb(1)-O(4) bond lengths are 2.07 Å. There are four inequivalent O sites. In the first O site, O(1) is bonded in a 5-coordinate geometry to one Na(1), one Na(2), one Mg(1), one Cu(1), and one Sb(1) atom. In the second O site, O(2) is bonded to one Na(2), two equivalent Na(1), one Mg(1), and one Sb(1) atom to form a mixture of corner and edge-sharing ONa3MgSb trigonal bipyramids. In the third O site, O(3) is bonded to one Na(2), two equivalent Na(1), one Mg(1), and one Sb(1) atom to form a mixture of corner and edge-sharing ONa3MgSb trigonal bipyramids. In the fourth O site, O(4) is bonded in a 5-coordinate geometry to one Na(1), one Na(2), one Mg(1), one Cu(1), and one Sb(1) atom.