Na3MgBiO4 crystallizes in the monoclinic Pm space group. There are three 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 in a distorted trigonal non-coplanar geometry to one O(4) and two equivalent O(3) atoms. In the third Na site, Na(3) is bonded in a distorted rectangular see-saw-like geometry to one O(1), one O(3), and two equivalent O(2) atoms. Mg(1) is bonded to one O(2), one O(4), and two equivalent O(3) atoms to form corner-sharing MgO4 tetrahedra. Bi(1) is bonded in a distorted see-saw-like geometry to one O(2), one O(4), and two equivalent O(1) atoms. There are four inequivalent O sites. In the first O site, O(1) is bonded to one Na(1), one Na(3), and two equivalent Bi(1) atoms to form ONa2Bi2 trigonal pyramids that share corners with four equivalent O(4)Na3MgBi trigonal bipyramids and corners with two equivalent O(1)Na2Bi2 trigonal pyramids. In the second O site, O(2) is bonded in a 6-coordinate geometry to two equivalent Na(1), two equivalent Na(3), one Mg(1), and one Bi(1) atom. In the third O site, O(3) is bonded in a 5-coordinate geometry to one Na(3), two equivalent Na(2), and two equivalent Mg(1) atoms. In the fourth O site, O(4) is bonded to one Na(2), two equivalent Na(1), one Mg(1), and one Bi(1) atom to form ONa3MgBi trigonal bipyramids that share corners with two equivalent O(4)Na3MgBi trigonal bipyramids and corners with four equivalent O(1)Na2Bi2 trigonal pyramids.
Na3MgBiO4 crystallizes in the monoclinic Pm space group. There are three 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 2.49 Å. Both Na(1)-O(2) bond lengths are 2.77 Å. Both Na(1)-O(4) bond lengths are 2.34 Å. In the second Na site, Na(2) is bonded in a distorted trigonal non-coplanar geometry to one O(4) and two equivalent O(3) atoms. The Na(2)-O(4) bond length is 2.22 Å. Both Na(2)-O(3) bond lengths are 2.39 Å. In the third Na site, Na(3) is bonded in a distorted rectangular see-saw-like geometry to one O(1), one O(3), and two equivalent O(2) atoms. The Na(3)-O(1) bond length is 2.33 Å. The Na(3)-O(3) bond length is 2.50 Å. Both Na(3)-O(2) bond lengths are 2.29 Å. Mg(1) is bonded to one O(2), one O(4), and two equivalent O(3) atoms to form corner-sharing MgO4 tetrahedra. The Mg(1)-O(2) bond length is 1.99 Å. The Mg(1)-O(4) bond length is 2.00 Å. Both Mg(1)-O(3) bond lengths are 2.04 Å. Bi(1) is bonded in a distorted see-saw-like geometry to one O(2), one O(4), and two equivalent O(1) atoms. The Bi(1)-O(2) bond length is 2.29 Å. The Bi(1)-O(4) bond length is 2.27 Å. Both Bi(1)-O(1) bond lengths are 2.24 Å. There are four inequivalent O sites. In the first O site, O(1) is bonded to one Na(1), one Na(3), and two equivalent Bi(1) atoms to form ONa2Bi2 trigonal pyramids that share corners with four equivalent O(4)Na3MgBi trigonal bipyramids and corners with two equivalent O(1)Na2Bi2 trigonal pyramids. In the second O site, O(2) is bonded in a 6-coordinate geometry to two equivalent Na(1), two equivalent Na(3), one Mg(1), and one Bi(1) atom. In the third O site, O(3) is bonded in a 5-coordinate geometry to one Na(3), two equivalent Na(2), and two equivalent Mg(1) atoms. In the fourth O site, O(4) is bonded to one Na(2), two equivalent Na(1), one Mg(1), and one Bi(1) atom to form ONa3MgBi trigonal bipyramids that share corners with two equivalent O(4)Na3MgBi trigonal bipyramids and corners with four equivalent O(1)Na2Bi2 trigonal pyramids.